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  • COMPRESSOR / CONDENSER DIAGNOSTIC FAQs - CONTENTS: These questions and replies can help determine why the outdoor compressor is not working, running intermittently, making noises, tripping the circuit breaker or blowing its fuse. We discuss compressor and condenser installation, diagnosis & replacement.
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HVAC compressor / condenser diagnostic questions & answers or FAQs:

This air conditioning repair article provides diagnostic questions & answers for the outdoor compressor / condenser unit used on air conditioners & heat pumps. These questions and answers help diagnose an compressor motor that is not working, compressor noises, condensing coil performance, or for heat pumps, outdoor coil icing.



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Diagnostic Questions & Answers for HVAC Compressors & Condenser Units

AC Compressor (C) D Friedman

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Question: My air conditioner compressor blew, the new system is icing up, what's going on?

I am a 100% service-connected disabled veteran who just spent over $3700. to replace a 4 ton trane xr12 air conditioner condenser and coil. My old condenser compressor blew up and the HVAC guy said it wasn't worth replacing since the unit was a 9 yr old r-22 system.

He talked me into a new trane xr13, 4 ton, r-410 condenser and a 5 ton evaporative coil for an extra $400. saying I'd get 10% more cooling capacity than the 4 ton coil. this was 5 weeks ago. three techs have been here since trying to figure out why the evaporative coil keeps icing up. the best cooling we get with the thermostat set at 72 degrees is only 15 degrees cooler than it is outside.this is with the front panel off the furnace.

With the panel in place, in 2 or 3 days the coil turns into a block of ice. even with the panel off, as the day wears on and the outside temperature drops, the inside temperature increases. right now, the thermostat is at 72, it's10:15 p.m. it's 73 degrees outside and 76 degrees inside.

The HVAC guys tried to blame my ductwork as unable to handle the airflow, then inadequate air returns, then too small a hole (10x12) above the coil going to the plenum. all solutions of course would require a 2nd mortgage. My response was . BULL. It's something they did wrong because before the compressor blew, if the outside temperature was 100 degrees, inside it was 78 degrees.(with the thermostat set at 72.

Not once in 9 years did it ice up or did I ever have to remove the front panel of the furnace to increase the airflow., It has to be one or both of the things they installed, like maybe a defective evaporator coil. Do you have any suggestions? Thanks - B.H.

Reply:

Cooling coil icing can be due to an improper refrigerant charge, inadequate air flow across the cooling coil, or a problem with a refrigerant metering device (or something else we haven't thought-of). Your HVAC guys might be right that your old duct system is not moving enough air across the coil, allowing it to ice up, but if that's the problem I'd ask them why they didn't think of that before selling you that extra big evaporative coil in the air handler.

In a good-working air conditioner or heat pump system the components need to be in balance: compressor/condenser, air handler/evaporator, and ductwork.

If we hold off on the blame game for a bit, let's see if you can increase the airflow across the coil. Often I find on older cooling systems that the return air opening was too small or the connections from return register to the air handler small or cramped or twisty. A very crude "test" that I do NOT RECOMMEND for more than a few minutes of test operation is to see if the coil ices up if someone leaves the air handler blower compartment door off - to maximize the return air opening.

Take a look under DUCT SYSTEM & DUCT DEFECTS for the article

: RETURN AIR REGISTERS & DUCTS,

and also take a look at COOLING COIL or EVAPORATOR COIL and at the article: FROST BUILD-UP on AIR CONDITIONER COILS for more help.

Finally, at RETROFIT SIZING for A/C or HEAT PUMPS we touch on the importance of balancing the system components during a retrofit or upgrade of an air conditioner or heat pump system.

Let us know what you find - we'll both learn something.

Question: compressor just runs for a few seconds, then cuts off; short cycling A/C compressor problems

My condenser starts for a few seconds then cuts off cycle continues - Anon.

my compressor fun has started to short cycle, it run for 2-3 min then shuts off for one second then restarts runs again then stops etc. with no funny sounds or noises - Don

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Reply:

It's not clear from your question where in the entire cooling system your unit's troubles begin, so I'd look at diagnostic tips that may explain your compressor/condenser short cycling are found at LOST COOLING CAPACITY. Certainly a compressor that is having trouble starting can be diagnosed at HARD STARTING COMPRESSOR MOTORS, if you're sure the trouble is outside.

Question: ice on the refrigerant line, no cooling in the house

My line set going to outdoor unit has ice on it. Lost cooling in house. What is the problem and is there anything I can do to fix the issue - Pat

Reply: check the indoor air handler for an ice-blocked coil

A problem with a refrigerant metering device (thermostatic expansion valve, capillary tube, etc), or even a dirty air filter can lead to improper metering of refrigerant into the indoor cooling coil, leading to icing; but other causes of ice formation include an improper refrigerant charge or even something as simple as missing refrigerant line insulation. But when you also lose cooling inside, I suspect an ice blocked coil. See FROST BUILD-UP on AIR CONDITIONER COILS

Question: Icing at the compressor; compressor not turning on?

the outside unit of the heat pump is icing up on the compressor - Steve 8/7/11

Hi my fan in my house goes on but my compressor unit does not all the electric seems to be fine . could it be my thermostat? - Sam 8/7/11

the accu very heat,although it is new gen. clean,2Tr LS-60psi & HS-100psi, - Anon 8/6/11

Reply:

Steve: icing at the compressor/condenser sounds like a refrigerant charger or refrigerant metering problem.

Sam: if your thermostat turns on the air handler but the compressor/condenser does not run, the problem is not the thermostat. Check out the diagnostic suggestiosn beginning at LOST COOLING CAPACITY (link at the "More Reading" links at the bottom of this article )

Anon: those pressures look kind of low, no? What does your HVAC tech say about normal for that system?

 

Question: what does it mean if the outside compressor seems to work ok if I cool it with a garden hose?

If my fan blade had slipped (now fixed) and the compressor was overworked, is it normal for a technician to cool it off with a garden hose? Thank you - Audra 6/12/11

Reply:

Audra, we've seen techs or homeowners cool down a compressor with a garden hose, but of course if the compressor is overheating because it's worn or damaged that fix is not at all lasting. In the case you describe, as long as the compressor/condenser fan was fixed, I am guessing that the tech just wanted to get things moving quickly again and didn't want to wait for the system to cool down normally.

Question: air conditioner air flow is reduced and air is not cold - cooling fan not running?

Blower fan running but reduced air flow (Dirty filter?) Air is not cold. System was on for a couple of hours when I noticed condenser fan. It was not running. Turned system off, waited a while, turned system on. Condenser fan hummed but was not turning. Used a BBQ fork (ok, not smart but I’ve never been accused of being too bright) to hit fan and it started. Still no cold air, ran for an hour, compressor fan motor and compressor VERY hot (Burned my fingers twice to confirm, that "not so bright thing again.”) Suggestions? - William 6/21/11

Reply:

William: when the outside compressor motor runs but the cooling fan does not, I suspect a bad start/run capacitor on the fan motor (if yours uses one) or a bad fan motor; sometimes it's a bad control board circuit. If (with power turned off for safety) the fan spins freely if pushed, the motor is probably not frozen; in that case also see if there is a motor overload reset switch that can be pressed.

Question: my A/C compressor trips the circuit breaker, what might be wrong?

my compressor shorts out my breaker, I tested the compressor with an ohm meter and reads voltage. what can it be? - Chico 7/1/11

Reply:

Chico: if your air conditioner compressor shorts out and trips the circuit breaker I'm afraid the compressor motor may be seized.

Question: squealing compressor fan, fan motor replaced, now unit is blowing hot air

Late last week, the fan on my outside unit began making a squealing sound and next morning the unit was blowing very warm air inside. I walked outside and found the
Fan had stopped but the motor seemed to still be running. I then shut the unit off and called a repair service to fix or replace the fan motor. Motor was replaced and seemed
to be working properly. Now, after 5 days of use, the fan has again stopped and the unit
is once again blowing hot air. Anyone have any suggestions? - Ronnie 7/3/11

Reply:

Ronnie: if your fan motor was replaced and the new motor has also burned up I wonder if there is a fan bearing problem or an obstruction that is causing a mechanical resistance that is overloading the fan motor?

Question: A/C unit has put an inch of water on the basement floor - what might be wrong?

Our unit seemed to not be working so I just checked in the basement sound the furnace. There is about an inch of water on the floor. I shut the unit off, will Be calling the repairman soon, but am curious what you think the problem may be. - Linda 7/9/11

Reply:

Linda: you are describing the indoor air handler unit for your air conditioning (see the article link at the "More Reading" links at the bottom of this article titled BLOWER FAN OPERATION & TESTING]

Water on the floor near your HVAC blower unit (or fan/coil unit or "indoor air handler" - all synonyms) could be from a condensate pump/drain that has stopped working or gotten clogged. Water in a condensate overflow pan will on some systems turn off the system by activating a float switch in the pan.

But another completely different condition - icing of the cooling coil - could also lead to water on the floor around the air handler when the system cycles off and the ice melts.

If your unit continued to run but was no longer cooling, I suspect this latter cause. Let us know what you find - it will help other readers.

Question: indoor fan runs, outdoor compressor won't turn on, thermostat not calling for cooling

Our fan is working on the inside, but the compressor unit will not turn on at all, so the air blowing is not cool. I've called multiple service techs, so far none can come out today (it is in the 90s!!), one MIGHT be able to come out tomorrow and I am waiting on a call back from another. Of course our house is on the market and we are supposed to have an open house tomorrow. Right now I have the whole system off at the thermostat, but keep hearing the inside system begin to start for about 5-10 seconds and then stop. Any tips to check? We've thrown the breaker to the furnace and the compressor. Our furnace is a dinosaur (but a strong one!!), the compressor unit is maybe 8 years old. - Laura 7/9/11

Reply:

Laura, I'm a little surprised that you are hearing the inside air handler running if your thermostat is not calling for cooling - could be a control problem. When a compressor won't start I first make sure there is power to the unit, which you seem to have done. Try the steps outlined in the article linked to at left of this page and titled LOST COOLING CAPACITY

Question: indoor fan runs but outdoor compressor is not spinning

My central air unit turns on, but the fan to the compressor is not spinning. Help!! - Robyn 7/26/11

Reply:

Robyn take a look at the compressor diagnostic steps suggested above: if the unit has power and your thermostat is calling for cooling but it doesn't turn on, the problem could range from a bad relay (minor expense) to a bad compressor (costly). You need a service call. But first be sure everything is turned on.

Question: noise from A/C compressor - fan had fallen off and therew was a burning smell

I investigated a noise coming from my compressor & found that the fan had fallen off and was lying at the bottom of the unit. There was a slight burning smell, but the motor still appeared to be running. I turned off the unit...Do you think the fan just needs to be reattached or does the entire motor need to be replaced? - Janet C 7/11/11

Reply:

Janet:
Good going on a commonsense investigation and diagnosis of a serious problem. Provided that the fan blades didn't damage any system components when the fan came off of the shaft, it MAY be possible to replace the fan and tighten the allen screw that holds it in place. But I'd want an expert inspection of the system before turning it back on. I'm worried that a spinning fan blade flopped around and cut a wire or damaged something.

Question: outside compressor runs but no air is coming out of air conditioning supply registers

my outside unit is running but there is no air being put out inside the house - Monica 7/20/11

Reply:

Monica,

If the compressor/condenser is running but the indoor air handler blower fan won't run you want to start diagnosing with the article linked to at the "More Reading" links at the bottom of this article titled

BLOWER FAN OPERATION & TESTING

Check for power on at the air handler
Check for a loose fan belt or pulley
Check for a blower fan motor that is off on thermal reset

Question: air conditioner was not blowing cold air, turned it off, now it is running again, then chugg chugg sounds

Its near 100 degrees again today. Last night the A/C to the bedrooms wasn't blowing cold air so I turned it off and everyone was uncomfortable sleeping. This morning I went outside to the compressor unit (I'd turned the system on inside) to find the fan blowing normally and the compresser trying to start but not getting there. It would "chugg-chugg" for a few seconds then stop. It retried after a little bit with the same "chugg-chugg then stop." Its a York System that came with the house. Any ideas? - Will Pollock 7/22/11

Reply:

Will: you are describing a hard starting A/C compressor. A hard start kit (capacitor) might get it going again; keep in mind though that a hard starting compressor may also be near end of life.

Question: old Lennox compressor died, glowing red pipe - is there a contamination worry in the A/C system?

I have a very old Lennox compressor unit that died 2 days ago. WHen trying to determine what was wrong I turned on the unit from inside the house and when I went outside to inspect it the smell of burnt oil was in the air. Then, when I looked at the condenser, the pipe looked like it was glowing red. So, it's now time to change the unit. My question is would the pipe to my furnace and the A unit be contaminated with oil and other chemicals from the compressor? Do I have to change the complete system, or can I simply replace the compressor unit? Thanks. - Pat 7/23/11

Reply:

Pat, in short, yes.

Your description of burnt oil smell and very hot A/C compressor parts is sure evidence of a motor burnup. And you're right to worry about contaminants in the refrigeration system after a compressor motor crashes. Even the smallest amount of debris can clog the refrigerant metering device - thermal expansion valve or capillary tube.

A proper repair that involves replacing a compressor includes drawing a vacuum on the system for long enough to get as much contaminated material out as possible, and also the installation of a special compressor burnout drier filter on the system to catch remaining debris that would otherwise be circulating around in the refrigerant piping and coils.

This drier is discussed in more detail at the article REFRIGERANT DRIERS & FILTERS (links at the "More Reading" links at the bottom of this article )

Question: trailer air conditioner not kicking in

Our air conditioner in our trailer is malfunctioning. The fan still blows wonderfully but the unit won't kick in. It tries and tries it just won't kick in. Any suggestioins - Cindy 7/27/11

Reply:

Cindy check out the diagnostic article titled DIAGNOSE & FIX AIR CONDITIONER / HEAT PUMP (link at the "More Reading" links at the bottom of this article ) and focus on compressor/condenser no-start problems. Could be a bad relay, start/run capacitor, or motor.

Question: My A/C unit kept blowing a fuse, now nothing runs

My Center A/C unit had a tuned up. I clean the evaporator, I put the blower down and put the new motor and clean the blades deeply, I have a clean filter, I clean the condenser deeply, and I bought a new thermostat. OK. The unit star running normally and you fill the normal warm air in the fan (outside) But 3 to 5 minutes later the heat in the condenser air increased suddenly the condenser stop with noise, and I need to turn it off. what is this? Please give me a clue? - Anon 6/28/22

I have a pretty old Tappan unit, and when the power goes out, if the A/C is running it will blow the fuse, usually we just replace the fuse, and now nothing will run on the A/C unit. any ideas? - Shantel 6/20/11

Reply:

Shantel:

Often when an A/C unit keeps blowing the fuse it's a sign that the compressor is drawing high amps which means it's jamming which, I'm sorry to say, means it's at end of its life. I'd have a service tech look at the unit; it might limp along for a while longer if s/he installs a hard-start capacitor kit. When "nothing runs" you may have meant that the fuse or breaker tripped enough times that you've lost power on that circuit.

Anonymous - from what you describe you need a service call from a trained HVAC tech.

Question: My hi line is cold, low line is warm and the condenser blows hot air

In my situation the high pressure line is colder than the low pressure line. The condensor coil blows mainly hot air, but the end closest to the compressor blows hotter air than the end furthest from the compressor line. Any suggestions? - Jim T. 7/13/11

Reply:

Mundo suggested: hey jim t check for restriction at the evaporator

Jim T:
Also, is your unit a heat pump or only an air conditioning system? - Editor. Let's be sure your system is in cooling mode.

Question: AC unit not cooling, very hot high pressure refrigerant line

our AC unit is not cooling, the high pressre line is VERY hot and the low pressure line is not much colder than room temp. last year we put in a new evap coil.. any ideas - Rusty 7/31/11

Reply:

Rusty, you need an expert on site to diagnose the problem. There are several problems that can give excessive pressure/temperature on the compressor outlet side of the system (the high side). Sounds like a blockage, maybe clogged dryer or bad refrigerant metering device, sometimes a clogged condensing coil.

Question: Outside AC turns on but no cool air is delivered inside. What's the cause?

our AC outside turns on but it does not blow any air inside what can be the cause of this? - Veronica 8/2/11

Reply:

Veronica if the outside compressor/condenser is working but the inside air handler/fan unit is not, take a look at the diagnostic article BLOWER FAN OPERATION & TESTING (links at the "More Reading" links at the bottom of this article )

It could be as simple as a fan drive belt that has broken in an air handler, or a dirty air filter.

Question: can't get up to working refrigerant pressure level

The discharge line from my condenser is giving only 100 PSI, even after adding R-22 to the low side. Is my compressor defective? - Carlos 8/11/11

Reply:

Carlos, could be a bad compressor but it could also be a bad thermostatic expansion valve that is not closing.

Question: new AC unit, has trouble starting up / compressor fan won't start

my air conditioner is new. its been hardly four month since i purchased it. most of the times it tries to start 2 to 3 time and then get started and some times unable to start. i dont have stablizer in my house for ac. when it runs it runs smooth and when it trips same case occur like starting can you please comment the possible casuse - Waquar Zaidi

(July 20, 2015) lewis said:
Took the top off the unit. The fans spins by hand but wont turn on and run. Could it be the condesor

Reply:

Lewis: if the compressor motor runs but the compressor/condenser fan won't run see FAN, COMPRESSOR / CONDENSER DIAGNOSTIC FAQs and check for a bad fan start run capacitor or a bad fan relay.

Wagar I'm surprised to read that a new A/C system compressor is not starting, but I suppose it could be a bad start capacitor or another bad control such as the Thermostatic Expansion valve. There are perhaps a few mistakes that could happen during installation that could destroy even a new A/C compressor such as dirt in the system or an improper refrigerant charge or a bad TEV that slugged the comprssor with liquid.

I'm unclear about the second and third sentences of your question.

Reader followup:

2nd and 3rd sentence i would like to elaborate: when compressor starts its working fine i mean it cools the room i use to run it on 26 degree centigrade and when thermostat trips and after 10 to 12 mints when compressor again tries to start same problem comes. and some time with out problem, compressor starts in first attempt. is this a compressor problem what will happen if i continue to run my ac in this situation. thanks in advance

Reply:

AHA Wagar,

I can't pretend we can really diagnose by e-text Q&A, but if I understand more clearly, you are saying that the A/C compressor starts and runs OK the first time, but after the thermostat is satisfied and stops the cooling system compressor/condenser, when the temperature in the building rises and the TT calls for cooling a second time, the compressor is having trouble starting.

A simplistic view would be to treat it as a "hard starting compressor" and install a hard start capacitor kit. But since the compressor starts OK cold, it might be a different trouble.

If the compressor is trying to re-start against high head pressure that is more difficult than starting "cold" when the refrigerant pressures are the same on both high side and low side of the system.

So I'd look into what would cause head pressure to remain high after the compressor stops running. In many HVACR systems, as soon as the compressor stops running the pressures begin to equalize on the two sides of the system.

See COMPRESSOR / CONDENSER DIAGNOSTICS

For more diagnostic help see the article REFRIGERANT PRESSURE READINGS and REFRIGERANT PRESSURE CONTROLS & SWITCHES

Reader followup:

Hi DanJoe, it even having same problem in first time start and now these days after its thermostat satisfies its not restarting after several attempts. what i am concerned is: is it a compressor problem? or capacitor. or possibly some thing else when ac start it works fine i am as far as cooling is concerned there is no problem with cooling once it get success in starting. - Waqar

Reply:

Waqar why don't you try a hard-start capacitor kit

Reader followup:

Thanks DanJoeFriedman i will definitely try actually i am away from my home town will reach in 15 days. i would like to thanks you for your support you provided and will let u know the results.

Question: start/run capacitor changed, but now nothing works

I changed equivalent capacitor after that it was ok to startup.
Now i need to turn on back, but it di dnot startup. i need to turn off siwtch then tunr on back switch in order to startup again.
Why is it?
Thanks, CHang - 8/26/11

Reply:

I'm not sure, Chang. Double check your capacitor to see that it's matched in rating to the original and that you wired it correctly.

Question: outside fan won't run, A/C is making a hissing noise

fan on outside unit does't run the ac runs but does not cool makes hissing noise - Nancy 9/7/11

Reply:

Nancy, See NOISES, COMPRESSOR CONDENSER (article link at the "More Reading" links at the bottom of this article ) to diagnose various A/C system sounds,

Watch out: If you hear a loud high pitched noise at the compressor, turn off electrical power to the unit immediately.

Other more quiet hissing noises from the air conditioner compressor motor may (if the motor is a reciprocating compressor) be due to leaky internal valves. The compressor motor makes a hissing sound all during the time the compressor is running; when the motor stops the hissing dies down fairly quickly as the high side and low side pressures equalize. In this case the condition may not be dangerous, just an inefficient system that is costly to operate.

Question: outside air conditioner compressor made a loud noise, then smoked, now it seems to be working

(Jan 4, 2015) linda cape said:
my compressor made a loud noice,then puff of smoke came out.I turned it off,when I turned it on again it worked and is heating.any known reason for this?

Reply:

Linda I dont know what happens but it doesn't sound good. If it was really smoke -as in something burning, I'd leave the unit off and ask for a service call.

Possibly it was not true smoke but a refrigerant leak which might, depending on leak rate and weather, might appear as white "smoke'. - Also a need for a service call.

it's also possible your system is running but on backup heat.

DO let us us know what your heating service tech finds as it will assist other readers. And do not avoid a service call since if there was a leak or burn-up the system may be unsafe.

Question: air conditioner compressor shuts down after 30 minutes or less - short cycling HVAC compressor / condenser unit

My compressor shuts down after only 30 minutes or less, it starts fine, but cooling seems to be a bit less then before, and none at all once it shuts down. I open the breaker for a short time and it will run again, then shut down. - Darrell M 9/8/11

(Aug 6, 2014) mike said:
my a/c,compressor stars up and runs for 5 minutes before stopping,it's cooling for those 5 minutes it's running.I did replace the 50+5 cap. but it did not make a difference.

Reply:

Darrell, it sounds as if a compressor motor may be overheating; when you leave power off for a time the motor cools down enough that its own internal thermal reset in fact resets itself. I'd call a service technician for more thorough diagnosis.

By no cooling, if you mean there is airflow but the air is not cool, that's consistent with above.

Mike: Check for an overheating motor or a control board or relay snafu

See HVAC COMPRESSOR SHORT CYCLING ON & OFF

Question: air conditioner or heat pump compressor / condenser won't shut off

(Apr 29, 2015) Raymond said:
My air conditioner compressor keeps running even when I put the thermostat on heat. I just had a new furnace installed this winter and there are two wires coming from the compressor one is red and one is white. I connected the whit to the letter "C" on the furnace and the red to the red wire. I tried to connect the white wire to the yellow, green and white wires but the compressor would not energize. when I connected the white wire to the "C" contact in the furnace the compressor came on runs fine and puts out cold air but will not shut down when I switch to heat?

Reply:

First check that the thermostat is set above room temperature or is in the OFF position.

Then see COMPRESSOR / CONDENSER DIAGNOSTICS where we include HVAC COMPRESSOR WON'T STOP

Question: My A/C compressor just won't stop running

I recently noticed my AC condenser unit still running when the system inside shutoff by itself. and also, does the condenser unit have to be leveled. I notice the slap which holding the unit is slopping. Any suggestions? Thank you. - Rick 8/16/11

Reply:

A/C compressor/condenser won't stop running:

Rick usually when an A/C condenser unit won't stop running even though the inside equipment has shut off by itself my thinking divides into two investigations:

- is there a problem with the INDOOR unit such as a blower fan that won't start, an access door switch open, a condensate drain switch turning off the blower unit - these can leave the system calling for heat and the compressor running (though that's not good for the compressor)

- is there a problem with the outdoor equipment such as a bad control relay or control board

See COMPRESSOR / CONDENSER DIAGNOSTICS

Question: the Haier AC unit is forming frost or ice on the coil

my question is i have turned off my 1 ton haier ac its inner unit is shut off but not outer unit due to which it it creates ice in inner unit can you let me know what is the issue. Thanks !! - Asim Niaz 9/15/11

Reply:

Asim, if the indoor blower unit is not running and the outdoor compressor is running the lack of air movement across the evaporator coil will lead to frost and ice formation on the coil. Under COOLING COIL or EVAPORATOR COIL you'll find diagnosis of ice or frost blocked cooling coils.

Question: I filled up my air conditioner with gas but now what?

So what is the solution of this problem as i have already filled gas recently. Thanks !! - Anon 9/16/11

Reply:

You need a service call from an experienced diagnostician. We don't have enough information about your case to specify a fix.

Or take a look at LOST COOLING CAPACITY for more diagnostic guides
(article link is at the "More Reading" links at the bottom of this article )

Question: replaced air conditioner compressor, new syste is icing up

Question: My air conditioner compressor blew, the new system is icing up, what's going on? add another return to it . may have to change duct size maynot if indoor unit is close to returns . hope that helps a bit - Chris 3/15/12

Reply:

Rooster said:

Sounds like you may have put a 1500HP Blown Hemi in a Volkswagen. One thing to try...did the installer select the proper fan speed for the air handler? If the fan is running in a slower speed (usually for heating, not A/C), air flow will be inadequate. But I'm betting on inadequate duct capacity. Probably should have stuck with the 4 ton evaporator coil. Sounds like an oversight or ignorance on the installers part to me. Also see COOLING COIL or EVAPORATOR COIL for our article on causes of cooling coil ice problems. Something as simple as a dirty filter or blower fan can cause the trouble.

Question: my central AC unit is blowing out black particles

My central ac unit is spewing out black particles. I got the blower and the duct cleaned for my whole apartment, but the ac is still blowing the black particles. Does anyone have any idea what it is and how I can get rid of it. Thanks - Amsa 5/6/12

Reply:

Amsa: about A/C blowing out black debris particles, check for damaged duct insulation, say from a mechanical cleaning operation, and of course be sure you've got a new clean air filter in place; The inspection in the air handler ought to include a check of bearings and moving parts for damage;

Question: My A/C capacitor burned up

My capacitor on my Trabe XL13i burned up along with all the wiring above it into the compressor area, it appears to have caused a fire, because it melted part of the outside of the unit case. Is it worth getting the wiring fixed and seeing if the rest of the machine still works or should we just call it quits and replace it? The air conditioner is 9 years old. - Shana5/16/12

Reply:

Shanna, about a burned up capacitor: it is possible for a capacitor to itself be the point of a failure; I'd try replacing the capacitor and any questionable wiring or connectors; let us know how that works.

Question: no cool air is blowing inside the house but outside compressor unit is running

No cool air blowing inside the house. The fan running outside is blowing cool air not hot/warm air. Not sure if it's a compressor issue. - Orios 5/29/12

Reply:

Orios, if the compressor motor never runs, but the air handler unit is running and the thermostat calls for cooling, the problem is at the compressor / condenser unit. See the diagnostics under "COMPRESSOR & CONDENSING COIL, A/C" (article link at the "More Reading" links at the bottom of this article )

Question: my 15 year old central air conditioner is running fine but I was advised to replace it to avoid risking refrigerant line contamination if the old compressor fails

I have 15 years old central AC unit. It is working fine. I was advised to replace it with a new one because there is a danger of refrigerant contamination of pipes if the old unit fails. If it happens,
to clean/replace pipes would cost additional 2000 dollars. How serious is it? - Salve 5/31/12

Reply:

Salve I think you should get advice from a different and more experienced HVAC tech. Like many a good lie, this one has some truth in it: if a compressor motor fails, burned oils in the refrigerant can contaminate the refrigeration piping - that's why when a burned out unit is replaced the tech will pull a vacuum on the system, do his/her best to clean the lines, and a special compressor burnout-filter or two will be installed on the refrigerant lines to protect the new motor and other parts from damage or debris clogging.

But a system can fail in a variety of ways, and as I explained there are well known means of dealing with debris in the system. What you were told would make me look elsewhere for my HVAC maintenance and repair services.

Question: My air handler works but the outside AC unit doesn't come on all the time - bad compressor?

my air handler works, but the outside ac unit does not come on all the time. It's intermintent. My HVAC guy did pressures and said I have a bad comprresser (20 year old unit) and I'm better off getting a new ac unit. Sometimes it will come on and stay on. Other times it will not come on at all. - JPI 6/16/12

Reply:

JPI, I'm in no position to second guess the expert who was on the scene - s/he sees clues and performs test way beyond what we can do in a text Q&A. But here are some thoughts:

a failing compressor motor can become increasingly hard to start; the tech can install a hard-start capacitor to get the motor running again - for a time - and it might be worth a try: that's an inexpensive part and usually fairly straight-forward to install.

Question: 8 year old TempStar Air conditionre troubleshooting

We had a service tech out for a inspection check up of our 8 yr old tempstar unit because we cannot seem to get the the house temp to the low 70s even when unit runs for 5+ hrs strait....
the tech said the coil needed cleaning or replaced and our compressor was not starting and that it was just humming & clicking when trying to start and recommended to us 2 options to remedy the problem...new compressor or new system and both were not cheap.

while he was testing the equip outside I was in my office and could hear and feel the vibration of the unit trying to start...

My son-in-law came over and we removed the coil and cleaned it thoroughly and then checked all the wiring on the outside unit compressor and found a green wire disconnected and stuffed into a hole (Hmmmmm!).
we reconnected the wire and fired the unit up and the compressor seemed to start with no problem ( no humming or clicking).

So, if it is 98F outside we cannot get the inside house temp below 79f,,I put a refrigerator thermometer in front of an air duct and left it there for 30+ minutes and then checked it....it read 61F...I am at a loss of what to do....also the blowing air pressure does not seem to be strong.......what to do??? - Doug S 6/24/12

Reply:

Doug the green wire is probably a ground that needs to be connected, but I'm doubtful that that will fix a humming compressor - more likely the compressor start/run capacitor is bad or the compressor motor itself is bad. It sounds as if there may be some risky do-it-yourself work going on - I'd call a trained HVAC tech at this point.

Question: metering device for refrigerant needs to match the condenser size (and evaporator coil size)

The metering devise need to mach condenser if is 4 ton set a 4 ton metering devise even on a 5 ton evaporator. - Anon 7/11/12

Reply:

Agree, though some TEVs can be adjusted within an operating range for most equipment in residential applications

Question: starting capactior uF microfarad measurements & tests

I am troubleshooting a 7500BTU Danby portable air conditioner (the tall vertical unit with ducting out the back via flexible hose). It appears that the compressor itself is at fault, but I would like to be sure before replacing the unit.

The start capacitor measures OK (meaures 46uF for a 45uF +/-5% unit) and appears in good condition. I measured the resistance between the three compressor terminals and they seem to be OK (C-S=2.8ohms, C-R=1.0ohms, S-R=3.7ohms) and there is high resistance between all terminals and ground. I applied 117Vac directly to the compressor (bypassing the control circuits) and the compressor just hums - the current draw was 30A. Being a protable unit, everything is jammed into the compartment and I don't see any way to access the compressor at all. I'm about to give up on the unit and look for a new one, but just wanted to see if there are any other things to try. The unit is probably about 9-10 years old, but has only seen regular use in the summer over the last 3 years.
Thank you for any help or advice.
Mike - 7/14/12

Reply:

I agree with your suspicion about the compressor. Often though a tech will just try swapping in a new start/run cap as a cheap simple test.

Question: air conditioner just blows hot air

air conditioner blowing hot air - Ann 8/4/12

Reply:

Ann,
with just the info you provided - blowing hot air - first make sure your thermostat is set to COOLING mode - and presuming it is and that all of the equipment inside and out are turned on, check

DIAGNOSE & FIX AIR CONDITIONER / HEAT PUMP

the article link found at the "More Reading" links at the bottom of this article - for a starting point in diagnosing why an air conditioner is not working.

Question: split system air conditioner stopped working - electric wires keep burning up at the terminals

My AC split unit stop working ,because the terminal wires connecting the compressor to the capacitor always burn this happen several times ,and the remedy was to replaced the burned wires,please can you advise what the reason that keep the terminal wire burn, the compressor is newly installed, Mohamed al lababidi -8/29/12

Reply:

Mohamed,

If the terminal wires keep burning up I suspect that the problem is one of

- an overcurrent - high amps draw because a motor is seizing and needs replacement - most likely it's this problem

- bad electrical connections, possibly involving alumnum wiring or loose connectors
- improper electrical wiring - such as undersized wires for the length of run, or mis-placed connections
- abnormal voltages in the system or voltage surges

Question: zero resistance test on AC compressor wiring

(Feb 11, 2014) Jerry Walch said:

I have always thought of this site as providing accurate information and have used it as a reference when writing technical articles. I'm having second thoughts. This (Zero resistance: If there is zero resistance the winding is open or broken) mistake appears in this article on How to Diagnose & Fix a Burned-out Air Conditioning. Zero resistance indicates a short circuit not an open circuit.

Reply:

Jerry,

You are quite correct that zero resistance means a connection is made and good, not open and broken' infinite resistance would indicate an open circuit. We've published nearly five thousand technical articles and are grateful for careful readers who occasionally find and help us fix a mistake. I trust that an error that slipped by in an article would not be enough to toss out the work of our many editors and contributors.

We welcome content critique, corrections, or suggestions by this comment form or by email. I have corrected the text, added a warning, and would welcome further comments. We've included a thank-you to you in our References section at the end of this article, keeping your ID private - let us know if you want to be identified by name in that part of the document. Thanks again,
Daniel

Question: AC compressor dead short to ground - rusty start capacitor

(Mar 7, 2014) Ricky Thompson said:

I recently had a compressor failure on my homes heat pump, the warranty sent a rookie out to inspect it. When the repair man shows up he asks me what kind of system I had, i told him a Trane heat pump. He then tells me he knows nothing about HP's.

Anyways he tells my warranty company that the start capacitor is completely rusted which is untrue it is rusty on top but surface rust, he also tells them that lady bugs and spider webs shorted out my board and tells them and improper installation of the cover let the water in to rust the cap. The cap tests fine, will this cause my compressor to short out?? The compressor is dead short to ground.

Reply:

Ricky I'm not sure about your message, but in general if a compressor measures as dead shorted to ground it's time for a new one; the compressor motor windings might burn out if the unit could not start because it lacked a working start capacitor. I'm curious about the capacitor test involved; in any case the compressor windings could short independent of the capacitor status as well.

Question: causes of repeated AC or heat pump compressor burn-out

(June 1, 2014) Voscar said:

I got unit complit burn, all the wire, contactor, i rewire the all. But i notes at list that is the 3'time happens. Firts time i believe the 30 amps breaker never open because, i can. See one left was burn in the electrict box. Somebody put two separate breaker each 20 amps. Is how i finded. I revomed does breaker instead i put only one of 30 amps.

This time the breaker wont open. But the main breker outside open, only one side i still got only 120 in the place instead 240. I disconect the unit sistem. To fixed that. Why only would open the breaker in one side. Not complit.

Reply:

Repeated compressor burn-out certainly means that there is another problem with the system that has not been found.

In addition to the burned out compressor you have faulty circuit breaker(s) that need to be replaced: tell me the circuit breaker and panel brand and I can comment further.

But the compressor burn-up is probably not caused by the circuit breakers but by an operating problem in the system - improper charge, setup, or control board. Possibly low voltage or a start capacitor problem.

Question: how do I know if a new AC or heat pump compressor is really needed?

(June 3, 2014) Dana said:

I have a 22 yr old 3 ton Goodman unit at my home in Dallas, Tx. It recently stopped cooling the house although the inside fan & outdoor unit seemed to be running fine. There was some cool air blowing inside but not enough to cool the house & temps inside kept increasing.

Didn't seem to be blowing as hard as normal thru the inside vents either. Turned unit off since it was doing no good anyway & to prevent possible additional damage.

Nothing was iced up on the outside unit and there was no moisture on visible lines. Prayed it just needed a Freon charge since I had just cancelled my AHS 1 month prior(Murphy's Law!). Friend hooked me up with a friend of theirs who works for AC company but moonlights on the side since I'm presently out of work. Guy comes out, tests something on side of house that is connected to outside unit then opens the side of the unit, tests a few things with a metering device & immediately says my compressor is shot. Shows me a wire running from compressor that is burnt up on the end as evidence.

I read that a clanking noise is a sign of compressor going out & it has been making a clanking noise for a while. Guy recommended replacing entire unit as the most cost-effective way to go since replacing the compressor, cleaning coils, etc would be almost as much as new unit. Said he can get the new unit with his discount for approx. $1,000 & will include warranty. Is he taking me for a ride or does he sound legit? Thanks in advance for your feedback!

(June 19, 2014) ken said:

bad compressor on 22 year old unit should i replace entire outside unit or just the compressor

Reply:

From what you describe I think the that you probably do need a new compressor/condenser unit.

Reader follow-up

Thanks! That's exactly what I did =)

Question: shorted, melted wires on Goodman AC unit

(June 19, 2014) Nick said:

I also have a Goodman central air unit. It was running fine but the wires going into the compressor corroded and shorted and melted the compressor terminals. My plan is to replace the compressor. Do I have to worry about burnt freon? And also my model H23B223ABCA compressor is obsolete. There is a replacement for it but do you know if I will have to change any of the plumbing? Or should it be pretty much plop it in kinda thing? I plan on having a tech doing the work.

Reply:

Nick,
The compressor replacement process should remove all refrigerant, pull a clean out vacuum on the system, and include burnout filter-drier canisters on the refrigerant lines to protect the repaired system. For a bad compressor burnout some techs return a year later to replace the filter-drier canister once again. Going all that you should be ok.

Question: loud compressor noises

(July 5, 2014) dan said:

my heater started making a loud noise while the air conditioner was running , the air unit stills runs but no air comes thru the vents and the heater makes all kinds of noise

Reply:

Dan

Watch out: I would TURN OFFall electrical power to the system promptly to avoid further damage or hazards.

It sounds as if the blower assembly is damaged.

Question: circuit board replacement on AC unit, now compressor needed

(July 14, 2014) Wendy said:

Second repair call in a month. First, not cooling--a board needed replaced, no additional freon added. Now HP compressor has a short and needs replaced. Trying to determine if it is better to replace entire outdoor unit. What are the chances that other components were damaged due to whatever caused this short before the unit started popping the breaker, whether from a power surge or attempting to run without enough freon or whatever?

Reply:

Wendy

Indeed the compressor is such a large part of the cost of the compressor/condenser unit that often it makes sense to replace the whole unit of an older installation. But we'd be more comfortable with some report on the cause of the compressor failure. For example a power surge may indeed have damaged other controls & parts.

Question: AC runs but air not cool at all registers, "blown to ground" (i.e. a short circuit)

Aug 8, 2014) Jennifer said:

Hi. My AC was running but not blowing at every vent and air was cooler on some vents then others . Technician saw ice and then came back and did a leak test and found no leaks. Then AC worked for a day but began to turn on and off periodically . Technician came back out and AC compressor turned on and off while he was here.

He put a booster on it and cold water because it was hot and then tested something and said it was blown to the ground. Home warranty won't pay for blown to the ground diagnosis. But it wasn't blown to the ground initially....right? Just trying to figure out if this makes sense or if warranty company is trying to get out of it. Thanks for your time.

Reply:

Jennifer

If the evaporator coil is icing over the system is not operating properly and may be low on refrigerant ( a leak someone has not yet found) or may have a failing refrigerant metering device.

Iced over coils can indeed also reduce air flow - but ALL of the air flow would be reduced not just air at some registers.

So I'd also look for open, loose, leaky, disconnected ductwork.

I have no idea what was meant by a "booster" added to the air conditioner, I don't know what "blown to the ground" means, but that sounds a bit like a short circuit and maybe the addition of a start capacitor to a compressor motor.

IF the AC compressor motor is not starting normally it may be damaged, at or near end of life.

Question: why does a blown compressor motor burn out wires?

11/13/2014 Deddy said:

About compressor burn out, i have outdoor unit Daikin VRV III RXQ16PAY1 and the compressor was burned out at cable lug compressor. how can it possible happen? (sorry for bad english)

Reply:

Deddy, a failing compressor motor can draw very high current (Amps) that in turn can certainly show up at a wire connector.

This is a companion article for COMPRESSOR / CONDENSER DIAGNOSTICS.

For diagnostic questions focused specifically on the outdoor condenser unit fan or fan motor, see FAN, COMPRESSOR / CONDENSER DIAGNOSTIC FAQs.

You may also want to see REPAIR & DIAGNOSTIC FAQs for A/C.

Question: compressor just runs for a few seconds, then cuts off; short cycling A/C compressor problems

My condenser starts for a few seconds then cuts off cycle continues - Anon.

my compressor fun has started to short cycle, it run for 2-3 min then shuts off for one second then restarts runs again then stops etc. with no funny sounds or noises - Don

Reply:

It's not clear from your question where in the entire cooling system your unit's troubles begin, so I'd look at diagnostic tips that may explain your compressor/condenser short cycling are found at LOST COOLING CAPACITY. Certainly a compressor that is having trouble starting can be diagnosed at HARD STARTING COMPRESSOR MOTORS, if you're sure the trouble is outside.

Question: ice on the refrigerant line, no cooling in the house

My line set going to outdoor unit has ice on it. Lost cooling in house. What is the problem and is there anything I can do to fix the issue - Pat

Reply: check the indoor air handler for an ice-blocked coil

A problem with a refrigerant metering device (thermostatic expansion valve, capillary tube, etc), or even a dirty air filter can lead to improper metering of refrigerant into the indoor cooling coil, leading to icing; but other causes of ice formation include an improper refrigerant charge or even something as simple as missing refrigerant line insulation. But when you also lose cooling inside, I suspect an ice blocked coil.

See FROST BUILD-UP on AIR CONDITIONER COILS

Question: ice build up inside the ductwork

I have ice build up on the inside of the furnace duct work. This will plug up the lines and the fans will not circulate thus stop blowing cold air

Reply:

If you find ice build-up inside the ductwork itself that's pretty unusual except in winter in freezing climates when moist air is rising into the duct system. Usually ice forms at the cooling coil in an air conditioner air handler or blower unit.

But I agree that ice can block air flow and more, when it melts, can cause water damage or even a mold problem in the building.

For more detailed advice please see WATER & ICE IN DUCT WORK.

To diagnose and fix ice formation on the cooling coil itself, see FROST BUILD-UP on AIR CONDITIONER COILS

Question: My A/C unit kept blowing a fuse, now nothing runs

My Center A/C unit had a tuned up. I clean the evaporator, I put the blower down and put the new motor and clean the blades deeply, I have a clean filter, I clean the condenser deeply, and I bought a new thermostat. OK. The unit star running normally and you fill the normal warm air in the fan (outside) But 3 to 5 minutes later the heat in the condenser air increased suddenly the condenser stop with noise, and I need to turn it off. what is this? Please give me a clue? - Anon 6/28/22

I have a pretty old Tappan unit, and when the power goes out, if the A/C is running it will blow the fuse, usually we just replace the fuse, and now nothing will run on the A/C unit. any ideas? - Shantel 6/20/11

Reply:

Shantel:

Often when an A/C unit keeps blowing the fuse it's a sign that the compressor is drawing high amps which means it's jamming which, I'm sorry to say, means it's at end of its life. I'd have a service tech look at the unit; it might limp along for a while longer if s/he installs a hard-start capacitor kit. When "nothing runs" you may have meant that the fuse or breaker tripped enough times that you've lost power on that circuit.

Anonymous - from what you describe you need a service call from a trained HVAC tech.

Question: My hi line is cold, low line is warm and the condenser blows hot air

In my situation the high pressure line is colder than the low pressure line. The condensor coil blows mainly hot air, but the end closest to the compressor blows hotter air than the end furthest from the compressor line. Any suggestions? - Jim T. 7/13/11

Reply:

Mundo suggested: hey jim t check for restriction at the evaporator

Jim T:
Also, is your unit a heat pump or only an air conditioning system? - Editor. Let's be sure your system is in cooling mode.

Question: water comes out of my system when I turn on the A/C

When i turn on the (AC Outside unit Lennox ) there is an overflow of water in my basement at the furnace which is a gas furnace- Don 7/24/11

Reply:

Don if you see water in your basement at the A/C unit when it's on, your condensate drain or pump is not working.

Question: No water is coming out of the condensate drain

water is not going through the drain hose - Anon 7/20/12

Reply:

Anon:

If you don't see condensate coming out of the condensate drain there are several likely explanations:

- the drain system for condensate has become clogged - you need to clear the drain line - check this first

- the system is off or not in cooling mode so not producing condensate

- the air is dry enough in your environment that not much condensate is being produced

- your system uses a condensate pump that has lost power or failed

Question: Is the problem with the fan motor or the compressor motor in my condenser unit?

I've a Lennox outside a/c unit. The fan/motor and compressor are part of the unit. The fan was not spinning and the A/c is not running. I've isolated the problem down to the fan/motor or the compressor, but don't know how to check or find out which it is. Any idea on how to check if the fan/motor is 'bad' or the compressor is 'bad'? - Fan or ... 7/23/11

Reply:

Fan or compressor: you could also have a bad control board, or relay switch in the compressor/condenser unit. If the fan is bad and the compressor is OK you'll hear the compressor turn on at the start of a cooling cycle, though a bad fan and system overheating could later cause some compressors to turn themselves back off. Similarly, if the compressor is bad your fan motor would still run. So I'm suspecting a control or switch problem./

Question: Our new AC won't keep running

uhm my A/C compressor broke about two weeks ago, we got a new one but when the fan starts the compressor works for a while and then it shuts down, and its turning on and off and i dont know whats wrong - Help. 7/25/11

Reply:

Help: if your new A/c won't keep running after it has just been installed, surely you should call the installer and expect it to be repaired under warranty - it's just been two weeks.

Even if all of the new equipment is in good condition, an example of a problem that could occur during compressor replacement is that contamination, moisture, dirt in the refrigeration system (which is made worse if a compressor burns up) can interfere with proper system operation.

Question: My AC won't work if I set the temperature down below 25C

my a/c is working properly when it is adjusted at 25 degree temprature, but if it is lower than 25, the compressor is disconnected by the overload protection. what is the problem with my a/c. - Mohamed 8/5/11

Reply:

Mohamed an A/C compressor may cut off on thermal overload due to overheating from local conditions around the compressor/condenser unit (no shade, very hot weather), an older motor that is failing, a start capacitor problem, or even a refrigerant metering device problem. If there's nothing obvious to you, I'd get a service tech to take a look. Keep us posted.

Question: Icing at the compressor; compressor not turning on?

the outside unit of the heat pump is icing up on the compressor - Steve 8/7/11

Hi my fan in my house goes on but my compressor unit does not all the electric seems to be fine . could it be my thermostat? - Sam 8/7/11

the accu very heat,although it is new gen. clean,2Tr LS-60psi & HS-100psi, - Anon 8/6/11

Reply:

Steve: icing at the compressor/condenser sounds like a refrigerant charger or refrigerant metering problem.

Sam: if your thermostat turns on the air handler but the compressor/condenser does not run, the problem is not the thermostat. Check out the diagnostic suggestiosn beginning at LOST COOLING CAPACITY (link at the "More Reading" links at the bottom of this article )

Anon: those pressures look kind of low, no? What does your HVAC tech say about normal for that system?

Question: My A/C compressor just won't stop running

I recently noticed my AC condenser unit still running when the system inside shutoff by itself. and also, does the condenser unit have to be leveled. I notice the slap which holding the unit is slopping. Any suggestions? Thank you. - Rick 8/16/11

Reply:

A/C compressor/condenser won't stop running:

Rick usually when an A/C condenser unit won't stop running even though the inside equipment has shut off by itself my thinking divides into two investigations:

- is there a problem with the INDOOR unit such as a blower fan that won't start, an access door switch open, a condensate drain switch turning off the blower unit - these can leave the system calling for heat and the compressor running (though that's not good for the compressor)

- is there a problem with the outdoor equipment such as a bad control relay or control board

Question: can the condenser get oil logged

can a condenser become oil logged, how and why? - Dominic 8/22/11

Reply:

Dom, it is normal for some refrigerant oil to circulate through the HVAC refrigeration system; Oil logging can occur in some installations if the refrigerant piping is not properly routed or due to an improper charge. The more usual problem is not at the condenser coil but at smaller orifices such as a cap tube or the TEV.

Dominic:

A condenser, if you mean the condensing coil, set level, would not be expected itself to become oil clogged, though condensers do sometimes clog from a combination of debris and moisture or oil.

But refrigerant oil moving through the system can clog a refrigerant metering device such as a capillary tube.

Question: our A/C compressor tries to start but then shuts right back off

I turned my AC on and noticed it wasn't getting cooler inside, I went out to the condensing unit and the compressor tries to kick on but then shuts right back off. Can not having enough refrigerant cause this? If not what's the deal? - Derek 8/22/11

Reply:

Derek, as another reader commented, your compressor/condenser may be having trouble starting. A start capacitor can sometimes fix this problem and give some added life to the unit.

Not having enough refrigerant would not itself prevent the compressor from starting, though there are some more technical connections one could draw (low refrigerant, sticking thermostatic expansion valve, high head pressure can mean hard starting - but that's not where I'd start).

Question: compressor starts, fan doesn't start, I hear a hissing

My compressor turns on but the fan does not turn(Ican turn the blades by hand) within 10 t0 15 seconds I get a long a loud hissssssssssssssssssssss.
Thanks foir you help
Henry - 9/8/11

I have some more info on my a/c when the a/c is turned on by dropping the temp in the house the compressor turns on but the fan does not turn, if you start to turn the fan by hand it starts spinning. When i turn it off by picking up the temp it stops. When i drop the temp again nothing goes on. If i wait a few minuites and try it again the compressor starts but the fan still has to be started by hand. Thanks for any help you can give

Reply:

Henry I suspect a bad fan start-run capacitor.

Question: no air is coming out of our supply registers

I have a coleman unit. Had heating probs 2 years ago leading to complete computer panel replaced, evaporator coils cleaner, gas regulator replaced. Two days ago, my A/C decided to stop working. I hear the freon flowing into the coil region, the fan outside is turning, but no air is coming out of registers. What can it be? - Cheryl 9/9/11

Reply:

Cheryl if you have no air coming out of supply registers the blower fan is not working or the duct system has become disconnected or blocked. Coil ice-over in the air handler can also block airflow. Start by determining that the blower is running and that the air filter is clean.

Question: water at the air return vent

what makes the water from an airconditioner build up in the return vent? - Connie Woyan 9/15/11

Reply:

Connie: if you see water at the return vent it may be condensation on a cool surface, or it could be condensate leaking down into the return vent from your air handler. You'll need to make a closer inspection of the air handler (blower unit) itself.

Question: what type of copper is used in HVAC refrigeration piping or tubing?

What is the content of copper tubes used in AC? (i.e I would like to know the contents of pipe which is being connected between the Fan and compressor of split AC) - Pratik Shah 10/1/11

Reply:

Pratik

Copper tubing used in A/C systems for refrigerant piping is just that. Soft flexible copper piping. While the differences between K, L, M and DWV copper piping are primarily in wall thickness, the the copper tubing alloy class may also vary for flexible copper tubing used in HVAC applications such as refrigerant piping and oil line piping.

1/2" K copper tubing has a wall thickness of about 0.049"
1/2" L copper tubing has a wall thickness of about 0.040"
1/2" M copper tubing has a wall thickness of about 0.028"

1 1/4" copper DWV piping has a wall thickness about the same as L copper or about 0.040"

The flexibility of copper tubing also depends on how it was produced: annealed vs drawn. Annealed copper is softer, suitable for flared and compression fittings, though it can also be soldered with proper edge smoothing/rounding.

Drawn copper is generally used for soldered fittings though drawn copper types A and B tubing can be joined with some types of compression fittings as well.

Details about the alloy mix of various copper piping materials is given by standard ASTM B88 and are providedin exhausting detail by copper dot org.

Question: no sweat on the suction line

what could be the problem when the sunction line of an air conditioner is not sweating? - Diana 2/3/12

Reply:

It may not be a problem - you'd need to describe the operating conditions in more detail. For example a cold suction line in low-humidity air may not collect much visible condensate.

Question: hard starting compressor

jon- ac system is less than a year old, when I turned on ac to check, condensor comes on then shuts back off, then 30-45 seconds after comes on again for 2-5 seconds. Whats wrong? - Jon Anon 8/18/12

Compressor on Lennox centeal air not turning even if the thermostat is activated.. It is blowing warm air.
Possible problem - Roger 7/8/12

Reply:

Anon: regarding your hard-starting compressor/condenser unit: we can't with confidence say what's wrong with so little information - your service tech can diagnose the problem, probably fairly quickly. But a common cause of the symptoms you describe is a bad start/run capacitor or worse, a failing compressor motor.

Todd said to Roger:

Rpger...not a professional myself but I had the same issue. The motor on my outside unit had worn out to the point that it needed to be replaced. Forturantely for me it was under warranty from a unit that I purchase 4-5 years ago. This might be strange for most units but we've had some above average summers here in Texas the last couple of years.
Another thing my HVAC tech does is check and replace the capacitor if necessary. I've been told that if the capacitor is shot, it will expand, almost resembling a coke can that is about to explode. Good luck.

Thanks Todd.

Roger, presuming you checked tonassure the unit has power and the thermostat is calling for cooling, if the suggestions in this article didn't get your system diagnosed check the LOST COOLING article linked above at the "More Reading" links at the bottom of this article - Editor

Question: does it help to spray the compressor/condenser coils when it's hot outside?

Does it help to spray water on the compressor coils when the outside air temp. is 100+? The inside air is going up in the afternoon to 82. - Greg Warner 7/7/12

Reply:

Some readers have reported that their compressor was overheating and ran ok when water cooled - this is perhaps a diagnostic step but not a reasonable repair. And don't soak electrical components.

Question: oil in the capillary tube? - recurrent cap tube clogging

i have replaced my compressor from company and when i started it was giving cool air but the copper pipe out side (large) was not cool enough and after 40 mints its timer light flashes and after 10 more mints its down automatically. it happens again and again i sent back it to company technician is looking into it.

He said oil was in capillary and it needs flushing so he will replace its capilary since after cleaning its not fixed. do u think there is no fault in compressor? or what possibly is the problem.. - Wagar 7/11/12

Reply:

You'll want to check the installation manual to find the control light decoding for your brand and model of cooling equipment. Could be a control or control board problem too. It's just about impossible to flush a cap tube so replacement is normal.

But if there is debris in the system, or excessive oil, the new cap can clog as well; good practice would be to empty the system, pull a vacuum, flush the whole system, install a filter dryer, replace the cap tube, and recharge.

Question: A/C not cooling, condenser fan not running

Several days ago I noticed that even though my air handeler was rinning the AC was not cooling, I foudn that the condensor was not turning, I flipped the breaker (that apprered to be in the on position) and it worked for awhile. 15 minutes later I noticed that the condenser was not operating again so I flipped the breaker again it corrected the problem. I then went on the replace the breaker which seemed to correct the problem, the AC worked normally for several days.

Now I find the condenser is not working again and flipping the breaker fails the correct the problem. When the condenser was working it was providing good normal cool air. The system is 2 years old. I assume I have an electrical problem in the condenser. What is likely to cause this problem and how can I test for it (I have a test meter) but I want to be careful because I know that a coil can retain a dangerous electrical charge even when all power is off and disconnected. - Rick 7/13/12

Reply:

typically we see if the fan spins, if it has power, and if the controls and fan contactor are bringing power to the fan when the condenser unit starts up.

Reader Followup

My problem turned out to be a bad contacter (damaged by ants) - Rick 7/13/12

Question: loud cricket chirping sounds at the compressor/condenser unit, and slow starting

outside unit making loud cricket sounding noise when running. Takes long time to come on when temp set low. - JT 7/276/12

Reply:

JT our link at the "More Reading" links at the bottom of this article NOISE AIR CONDITIONER / HEAT PUMP provides noise diagnostics.

About taking a long time for the A/C to "come on" when the temperature is set low: the thermostat is operating like an "on-off" switch that turns the air conditioner system on and off in response to room temperature. It's not an accelerator. So if there is an operating problem related to the system controls, the number of degrees below the room temperature to which the thermostat is set should make no difference in how long it takes the A/C system to start. As long as the SET temperature is lower than the room temperature the cooling system will turn on.

Question:

(Mar 19, 2014) Anonymous said:

I want to know the difference between inverters and todays airconditioner. what are the comm on defects of inverters and what refrigerant is use

Reply:

x

Question: Split AC system cools OK at night but not in afternoons

(May 24, 2014) Knight said:

Any body tell me what is the problem with my split ac It gives perfect cooling in night and morning but in afternoon its compressor turn on and off every after 15 minutes it can not give cooling from 2PM TO 6PM.. I checked gas, capacitor and connection and voltage its ok but i dont know whats the problem if you have any idea plz share with me

Reply:

Knight, as afternoon is the time the system works hardest I suspect the compressor motor is shutting down on thermal overload. If cooling it off with a water spray (DO NOT spray electrical components) that's likely to be the problem.

Question: how long should the AC run when first turned on

Anon said

when you turn on the AC for the first day of summer or heat how long would the unit circulate air then when does it stop

Reply:

The length of time that the A/C will run depends on many factors including

- the thermostat set temperature
- the building temperature at time the A/C is tuned on
- the efficiency of and cooling power (BTUS) of the system
- where the air is delivered
- thermostat location
- the thermal mass of the building: what materials have been heated up and need to be cooled down
- the heat gain rate of the building
- outdoor temperature, wind, and sun exposure

The air will circulate and the A/C will run until the thermostat is satisified. If the system cannot satisfy the thermostat for any reason the system will keep running.

Question: AC Fan runs 5-10 minutes then stops

(June 14, 2014) Scott said:

AC system starts (cools, fan runs, etc.), fan runs for 5 to 10 minutes then stops. No circuit breaker trips or electrical issues at the panel. Should I replace the fan motor?

Reply:

x

Question:

(June 16, 2014) amit said:

Please help, My AC compressor starts when i power it on and works perfectly but cuts off prematurely within 5 min. Compressor starts only after 2 hours however fan runs continuously. I also tried switching off and on but of no use. Had there been a problem in the compressor, why its working fine for 5 minutes after approx every two hours. Also You can understand that within 5 minutes thermostat also can't cut as cooling of room is also partial. please help I

Reply:

Amit

Possibly the motor is overheating, then binding, drawing high current, shutting down. Try cooling the outdoor unit with a water spray. If cooling the outdoor unit (designed to tolerate rainfall) changes its operation that is probably a diagnostic clue.

Question: where to buy a replacement control for a sticking Amana AC contactor relay

(June 21, 2014) Joey Payne said:

Older Ammana unit still runs and cools well contact sticks and overheats. Sticking causes outside unit to continue to run contact burns and burning wire.

Reply:

Perhaps your HVAC supplier can offer a generic replacement relay or entire control

Question: water at the base of the compressor

(June 30, 2014) Anonymous said:

Is it normal for there to be water coming out of the base of my compressor

Reply:

Anon

Water at the outdoor compressor condenser is probably coming from melting ice or frost. If you see cycles of significant ice or frost build-up the refrigerant charge or metering may be incorrect and I'd ask for a check by an HVAC tech.

Question: Window AC unit keeps automatically resetting its temperture control up to a high number

(3 days ago) Mary said:

Why would my window unit automatically keep going up to 86 degrees?

Reply:

I don't know, Mary. If you mean that a manual control is changing its setting from where you set it I suspect someone else is involved.

Question: how does a low refrigerant charge cause the coil to ice-up

7/11/14 Bob said:

How does a low amount of refrigerant entering the evaporator coil cause it to ice up?

Reply:

Bob, low refrigerant means too little in the cooling coil, lower evaporation temperatures, ice formation. Details of the explanation begin at

FROST BUILD-UP on AIR CONDITIONER COILS

And at REPAIRS for FROST / ICE on COIL we include a more technical explanation titled

Reader Question: why does a low refrigerant charge cause frost to show up on the coil ?

Question:

(July 13, 2014) Anonymous said:
i have a Carrier heat pump that i cant get the blower to come on. I have replaced the board and thermostat and not sure what to do next. Any suggestions?

(Aug 2, 2014) Lou said:
I have a carrier condensing unit that the compressor wont start.I have voltage at the contactor and have replaced the start cap and run cap.odd to say,im drawing 11 amps on start and run wires coming from the contactor but i hear nothing from the compressor! any suggestions?

Reply:

Lou

Check for a bad start relay

Question: how to monitor energy use on a shared AC unit

(Aug 11, 2014) Michelle Mell said:
I live in an apartment...home that was converted to two units. We share the outside AC unit. We each have our own thermostat. Is it possible to seperate so that each of the two units pays for their own electricity with that one AC unit? I mean can the power be split so to speak so that each apartment unit only pays for the cooing for their apartment?

Reply:

Michelle

In Europe energy use monitoring by individual apartment is required by law. If you live in the U.S. or Canada or Latin America that requirement is not given. A landlord could add equipment to monitor the time your thermostat calls for coolingh but that'd be an uncommon level of detail.

Question: compressor won't run until it's cooled down

(Aug 14, 2014) Andre Matthew said:
my AC is not cooling well don't know the problem with that.

(Aug 21, 2014) Wayne said:
When unit is cold it will start and run. After an hour the cooling fan stops but the compressor continues for a short time then quits. It will continue to start but will not start and run until it cools down.
Any ideas?

Reply:

Look for an overheating fan motor, relay or control board or possibly a refrigerant metering valve that is sticking.

Question: service tech says it may take hours after repair before cool air comes out of the system

(Aug 23, 2014) Anonymous said:
I just had a bad capacitor replaced in my Trane heat pump. Technician said it will take 7-8 hours before it begins to blow cool air. Outdoor compressor and fan are running, but air blowing out vents is still warm. Does it seem right that it would not blow cool air pretty quickly?

Reply:

Anon

I don't blame the service tech for being conservative - not wanting to be called back unnecessarily, but I'm surprised that she thinks it's going to take 8 hours for a heat pump to blow cool air. It might take hours to cool down a hot humid house and it can take some time to cool down even hot ductwork, but cool air ought to be coming out of the supply registers within less than an hour of turning the system on - just giving time to get past the effects of hot ductwork and air handler parts from having sat off for a time.

I suspect that 7-8 hour guess was more designed to give the service tech time to get out of town.

If after 20 minutes (I'm going out of town too after this note) NO cool air is coming out of your supply registers, call the service manager of your heat pump repair company and politely ask for some more experienced advice.

Question:

(Aug 27, 2014) paris said:
i have problem with my air condition unit...i replace motor... conect capasitor with 2 wires from motor... and black to black and purple to nutural and one purple from compresor to capasitor ..the fan starts but compresor is not working ..did id id anything wrong

(Sept 2, 2014) Anonymous said:
John Powers:

I live in Thailand and in very heavy rain the rainfall off the roof of the house splashes down hard all over the compressor, even from the side. The only way to prevent it would be to install a lot of spouting or move it to a southern exposure. Is it necessary? I have used it almost 24 hours a day for 3 years, and it works fine, though when repairmen recently cleaned it, afterwards there was a mildew smell, which eventually went away.
(Sept 23, 2014) Anonymous said:

(Sept 23, 2014) Anonymous said:
my handler has sweat and condensation on the outside

Question:

(Sept 21, 2015) Edward Bunn said:
Zone v. Phase
I have a heat pump. It is set up and has always operated as a two-zone system. One zone is upstairs and the other is down stairs. Each zone has a separate thermostat.
I just purchased a replacement pump for $7,000. I purchased a SEER-18, which is a high efficiency system. I understand that what makes it efficient is that is operates in two phases. Initially, it starts up at a lower power before powering to a higher power, thus saving energy and money.

The installer now tells me that he needs another $1,500 to get the phases to work. First, he said the new system did not have a zone board (zone issue), which I priced on the internet for $169. Now, he says he needs to install dampers, which only controls the amount of air flow to a space (zone) and cost less than $75 (Home Depot). Dampers really just control the amount of air in a particular zone of the home. These are already in my home. They relate to air zones and not start-up power. In my case, they control the air flow alternatively for the air upstairs and downstairs.
What am I missing? Am I being conned?

Reply:

I would ask for help from the service manager.

Question: Is the problem with the fan motor or the compressor motor in my condenser unit?

I've a Lennox outside a/c unit. The fan/motor and compressor are part of the unit. The fan was not spinning and the A/c is not running. I've isolated the problem down to the fan/motor or the compressor, but don't know how to check or find out which it is. Any idea on how to check if the fan/motor is 'bad' or the compressor is 'bad'? - Fan or ... 7/23/11

Reply:

Fan or compressor: you could also have a bad control board, or relay switch in the compressor/condenser unit. If the fan is bad and the compressor is OK you'll hear the compressor turn on at the start of a cooling cycle, though a bad fan and system overheating could later cause some compressors to turn themselves back off. Similarly, if the compressor is bad your fan motor would still run. So I'm suspecting a control or switch problem./

Question: Our new AC won't keep running

uhm my A/C compressor broke about two weeks ago, we got a new one but when the fan starts the compressor works for a while and then it shuts down, and its turning on and off and i dont know whats wrong - Help. 7/25/11

Reply:

Help: if your new A/c won't keep running after it has just been installed, surely you should call the installer and expect it to be repaired under warranty - it's just been two weeks.

Even if all of the new equipment is in good condition, an example of a problem that could occur during compressor replacement is that contamination, moisture, dirt in the refrigeration system (which is made worse if a compressor burns up) can interfere with proper system operation.

Question: My AC won't work if I set the temperature down below 25C

my a/c is working properly when it is adjusted at 25 degree temprature, but if it is lower than 25, the compressor is disconnected by the overload protection. what is the problem with my a/c. - Mohamed 8/5/11

Reply:

Mohamed an A/C compressor may cut off on thermal overload due to overheating from local conditions around the compressor/condenser unit (no shade, very hot weather), an older motor that is failing, a start capacitor problem, or even a refrigerant metering device problem. If there's nothing obvious to you, I'd get a service tech to take a look. Keep us posted.

Question: our A/C compressor tries to start but then shuts right back off

I turned my AC on and noticed it wasn't getting cooler inside, I went out to the condensing unit and the compressor tries to kick on but then shuts right back off. Can not having enough refrigerant cause this? If not what's the deal? - Derek 8/22/11

Reply:

Derek, as another reader commented, your compressor/condenser may be having trouble starting. A start capacitor can sometimes fix this problem and give some added life to the unit.

Not having enough refrigerant would not itself prevent the compressor from starting, though there are some more technical connections one could draw (low refrigerant, sticking thermostatic expansion valve, high head pressure can mean hard starting - but that's not where I'd start).

Question: compressor starts, fan doesn't start, I hear a hissing

My compressor turns on but the fan does not turn(Ican turn the blades by hand) within 10 t0 15 seconds I get a long a loud hissssssssssssssssssssss.
Thanks foir you help
Henry - 9/8/11

I have some more info on my a/c when the a/c is turned on by dropping the temp in the house the compressor turns on but the fan does not turn, if you start to turn the fan by hand it starts spinning. When I turn it off by picking up the temp it stops.

When I drop the temp again nothing goes on. If I wait a few minuites and try it again the compressor starts but the fan still has to be started by hand. Thanks for any help you can give

Reply:

Henry I suspect a bad fan start-run capacitor.

Question: no air is coming out of our supply registers

I have a coleman unit. Had heating probs 2 years ago leading to complete computer panel replaced, evaporator coils cleaner, gas regulator replaced. Two days ago, my A/C decided to stop working. I hear the freon flowing into the coil region, the fan outside is turning, but no air is coming out of registers. What can it be? - Cheryl 9/9/11

Reply:

Cheryl if you have no air coming out of supply registers the blower fan is not working or the duct system has become disconnected or blocked. Coil ice-over in the air handler can also block airflow. Start by determining that the blower is running and that the air filter is clean.

Question: water at the air return vent

what makes the water from an airconditioner build up in the return vent? - Connie Woyan 9/15/11

Reply:

Connie: if you see water at the return vent it may be condensation on a cool surface, or it could be condensate leaking down into the return vent from your air handler. You'll need to make a closer inspection of the air handler (blower unit) itself.

Question: what type of copper is used in HVAC refrigeration piping or tubing?

What is the content of copper tubes used in AC? (i.e I would like to know the contents of pipe which is being connected between the Fan and compressor of split AC) - Pratik Shah 10/1/11

Reply:

Pratik

Copper tubing used in A/C systems for refrigerant piping is just that. Soft flexible copper piping. While the differences between K, L, M and DWV copper piping are primarily in wall thickness, the the copper tubing alloy class may also vary for flexible copper tubing used in HVAC applications such as refrigerant piping and oil line piping.

1/2" K copper tubing has a wall thickness of about 0.049"
1/2" L copper tubing has a wall thickness of about 0.040"
1/2" M copper tubing has a wall thickness of about 0.028"

1 1/4" copper DWV piping has a wall thickness about the same as L copper or about 0.040"

The flexibility of copper tubing also depends on how it was produced: annealed vs drawn. Annealed copper is softer, suitable for flared and compression fittings, though it can also be soldered with proper edge smoothing/rounding.

Drawn copper is generally used for soldered fittings though drawn copper types A and B tubing can be joined with some types of compression fittings as well.

Details about the alloy mix of various copper piping materials is given by standard ASTM B88 and are providedin exhausting detail by copper dot org.

Question: no sweat on the suction line

what could be the problem when the sunction line of an air conditioner is not sweating? - Diana 2/3/12

Reply:

x

Question: hard starting compressor

jon- ac system is less than a year old, when I turned on ac to check, condensor comes on then shuts back off, then 30-45 seconds after comes on again for 2-5 seconds. Whats wrong? - Jon Anon 8/18/12

Compressor on Lennox centeal air not turning even if the thermostat is activated.. It is blowing warm air.
Possible problem - Roger 7/8/12

Reply:

Anon: regarding your hard-starting compressor/condenser unit: we can't with confidence say what's wrong with so little information - your service tech can diagnose the problem, probably fairly quickly. But a common cause of the symptoms you describe is a bad start/run capacitor or worse, a failing compressor motor.

Todd said to Roger:

Rpger...not a professional myself but I had the same issue. The motor on my outside unit had worn out to the point that it needed to be replaced. Forturantely for me it was under warranty from a unit that I purchase 4-5 years ago. This might be strange for most units but we've had some above average summers here in Texas the last couple of years.
Another thing my HVAC tech does is check and replace the capacitor if necessary...I've been told that if the capacitor is shot, it will expand, almost resembling a coke can that is about to explode. Good luck.

Thanks Todd.

Roger, presuming you checked tonassure the unit has power and the thermostat is calling for cooling, if the suggestions in this article didn't get your system diagnosed check the LOST COOLING article linked above at the "More Reading" links at the bottom of this article - Editor

Question: does it help to spray the compressor/condenser coils when it's hot outside?

Does it help to spray water on the compressor coils when the outside air temp. is 100+? The inside air is going up in the afternoon to 82. - Greg Warner 7/7/12

Reply:

Some readers have reported that their compressor was overheating and ran ok when water cooled - this is perhaps a diagnostic step but not a reasonable repair. And don't soak electrical components.

Question: oil in the capillary tube? - recurrent cap tube clogging

i have replaced my compressor from company and when i started it was giving cool air but the copper pipe out side (large) was not cool enough and after 40 mints its timer light flashes and after 10 more mints its down automatically. it happens again and again i sent back it to company technician is looking into it. He said oil was in capillary and it needs flushing so he will replace its capilary since after cleaning its not fixed. do u think there is no fault in compressor? or what possibly is the problem.. - Wagar 7/11/12

Reply:

You'll want to check the installation manual to find the control light decoding for your brand and model of cooling equipment. Could be a control or control board problem too. It's just about impossible to flush a cap tube so replacement is normal. But if there is debris in the system, or excessive oil, the new cap can clog as well; good practice would be to empty the system, pull a vacuum, flush the whole system, install a filter dryer, replace the cap tube, and recharge.

Question: A/C not cooling, condenser fan not running

Several days ago I noticed that even though my air handeler was rinning the AC was not cooling, I foudn that the condensor was not turning, I flipped the breaker (that apprered to be in the on position) and it worked for awhile. 15 minutes later I noticed that the condenser was not operating again so I flipped the breaker again it corrected the problem.

I then went on the replace the breaker which seemed to correct the problem, the AC worked normally for several days. Now I find the condenser is not working again and flipping the breaker fails the correct the problem. When the condenser was working it was providing good normal cool air.

The system is 2 years old. I assume I have an electrical problem in the condenser. What is likely to cause this problem and how can I test for it (I have a test meter) but I want to be careful because I know that a coil can retain a dangerous electrical charge even when all power is off and disconnected. - Rick 7/13/12

Reply:

typically we see if the fan spins, if it has power, and if the controls and fan contactor are bringing power to the fan when the condenser unit starts up.

Reader Followup

My problem turned out to be a bad contacter (damaged by ants) - Rick 7/13/12

Question: loud cricket chirping sounds at the compressor/condenser unit, and slow starting

outside unit making loud cricket sounding noise when running. Takes long time to come on when temp set low. - JT 7/276/12

Reply:

JT NOISE AIR CONDITIONER / HEAT PUMP provides noise diagnostics.

About taking a long time for the A/C to "come on" when the temperature is set low: the thermostat is operating like an "on-off" switch that turns the air conditioner system on and off in response to room temperature. It's not an accelerator. So if there is an operating problem related to the system controls, the number of degrees below the room temperature to which the thermostat is set should make no difference in how long it takes the A/C system to start.

As long as the SET temperature is lower than the room temperature the cooling system will turn on.

...

HVAC Compressor / Condensing Unit Diagnostic Articles

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Continue reading at COMPRESSOR / CONDENSER DIAGNOSTICS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see BURNED-OUT COMPRESSOR

Or see CAPACITORS for HARD STARTING MOTORS to try to kick start a reluctant compressor motor

Or see FAN, COMPRESSOR / CONDENSER DIAGNOSTIC FAQs for questions and answers about the compressor / condenser unit fan or fan motor.

Or see REPAIR & DIAGNOSTIC FAQs for A/C for questions & answers that help diagnose a broad range of air conditioner or heat pump problems.

Also see COMPRESSOR / CONDENSER DIAGNOSTIC FAQs

Also see REFRIGERANT DIAGNOSTIC FAQS

Also see REFRIGERANT PIPING INSTALLATION FAQs

Or see SLAB DUCTWORK
 

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