Photograph of  This new compressor was placed directly against
a brick wall. One third of its condenser coil cooling ability was blocked.Air Conditioner & Heat Pump Troubleshooting FAQs
Troubleshoot Air Conditioners & Heat Pumps Set#3

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Air Conditioning & Heat Pump FAQs

Questions & answers about fixing problems with air conditioners & heat pumps.

Third set of A/C & heat pump questions & answers can often help you diagnose air conditioning & heat pump system issues.

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Air Conditioning & Heat Pump Troubleshooting FAQs-1

Flex duct in a horrible routing of excess lengths (C) Daniel FriedmanThese questions & answers about diagnosing trouble with air conditioners and head pumps were originally posted at AIR CONDITIONING & HEAT PUMP SYSTEMS

A good place to look for diagnostic procedures is DIAGNOSTIC GUIDES A/C / HEAT PUMP.

Also see this series of A/C & Heat Pump Diagnostic FAQs sorted by major topic area are given at AIR CONDITIONING & HEAT PUMP SYSTEM FAQs LIST

On 2012-06-05 by (mod) - our AC has lost cooling capacity

Our AC: about "our AC has lost cooling capacity"

in the article above we list "what could be the issue" - I'm afraid that if you've read through and been through all of those diagnostics, it's time to call in an expert HVAC technician to diagnose the problem and then to describe the repairs s/he recommends.

WB: I can only guess with so little info, but if your A/C system has a condensate pan that uses a condensate pan overflow safety switch, then that could be shutting your system down. If the condensate pan stops draining - say from a clogged drain - the switch senses water accumulating in the pan and will turn off the system to avoid flooding the building.

Or it could be a different problem. It's time for your maintenance people to bring in someone who is qualified on air conditioning diagnosis and repair.

On 2012-06-05 by Our ac has lost cooling capacity

I checked all of the basic things, changed filters, replaced thermostat, etc. We changed the compressor last year. The shut off valve seems to be okay. And, we replaced the attic fan last month. What could be the issue??

On 2012-06-04 by WB

I live in an apartment complex and this weekend the air conditioner stop blowing cool air. I called maintenance and they came over to repair the problem. He removed some plastic tube and drained water from it and said that was the problem. Two hours later it stops blowing cool air again

. Needless to say, I called them back over and he informed me that I would have to drain that tube (line) ever time it goes out or call them. Is this correct? Should I have to drain a tube (line) for my air conditioner to work properly?

On 2012-06-02 by (mod) - no cool air on some floors

I'd double check that ALL of the air conditioning is provided really by a single system and that your thermostat is set on COOL not FAN.

On 2012-06-02 by AC

I have a duplex that has both levels sharing one central air unit. The upper level is working perfect. The lower levels air is blowing fine but the air isnt cool at all.

On 2012-06-01 by (mod) -


Use the on page search box to find our article COMPRESSOR & CONDENSING COIL, A/C and you 'll see a FAN diagnostic article series - or see the links at the end of this page

On 2012-05-31 by Anonymous

Heat pump fan not turning

On 2012-05-29 by (mod) -

Long running without cooling adequately could be due to many of the possible explanations we list in the article above; Check the output air temperature at the cooling coil to be sure it's actually cooling, and if so, check for air flow restrictions like a dirty filter. If the system used to cool the building adequately under the same weather conditions, we tend not to suspect that it was under-sized and we look for an operating problem.

On 2012-05-26 by Marty

I have the A/C thermometer inside set at 78 degrees. The temperature in the house is at 82 The unit continues to run but doesn't seem to cool enough to reduce the inside temp. I worry that it's running much too long. Help!

On 2012-05-26 by adam

a/c is not blowing cold air pipes and gages or freezing up

On 2012-05-25 by lee curtis

blower is working, air is ice cold, but it will shut it self off for a while or two to three days and then come on

On 2012-05-25 by (mod) - frost on AC coils


Use the on page search box to find the article titled "FROST BUILD-UP on AIR CONDITIONER COILS"

On 2012-05-23 by stacy evans

what does it mean if the ac is freezing and not cooling and its turned off but still running and i had work on it 10/28/2010

On 2012-05-13 by Heatpump not turning on

Indoor airhandler runs fine, heatpump won't turn on when thermostats calls, Heatpump will turn on when I push contact switch outside, I suspect control board on unit, any suggestions? Thanks!

On 2012-04-10 by Dave

Last summer I noticed small black specs of oily feeling water coming from my drain pipe on central air unit. What could this be? Also noticed sooty build up in my actual floor dehumidifer?

On 2012-04-03 by joe

why do i have to reset my a/c mode when i start my a/c

On 2012-02-17 by Lisa

I was told that on my 15 yr hold heat pump that the amperage was increasing while the compressor ran and that is a sign that the compressor is going bad. Can not find any info on if that is true. Help.

On 2012-01-29 by Matthew Knowles

I have a split ducted heat pump a/c unit. working correctly on cooling, good refrigerant levels, good outlet temperatures.

When I turn over to heating the outlet temperatures are too low. Maximum of 24 degrees celsius. the temperature of the five eighth pipe at the condenser unit is around 80 degrees celsius( good) but at the indoor connection is only 42 degrees celsius, could this mean a blocked or partially blocked evaporator internally?

On 2012-01-26

by steve lane

my wall/window a/c no cold air it does run hot can hear compressor run for hot only

On 2011-11-18 09:57:19.768049 by Arthur Lowe - refrigerant slugging?

Is it possible for an electrical utility failure,( ie. power surge, or rapid voltage fluctuations caused by storm damage to utility lines) which would cause a home refrigerator to start/stop rapidly resulting in any condition which would damage the compressor or cause a surge in high pressure to the refrigerant loop and subsequently cause a leak and loss of refrigerant?

Could it cause "slugging of refrigerant and subsequent high pressure and a failure of the integrity of the loop?

I know it's a long question. I had a properly working refrigerator and after a severe ice storm in NJ where power was coming on and off rapidly the refrigerator failed.

My issue is with the insurance company who needs to be convinced that this was possible.

A service tech said I have system leak and i should replace the unit.
All comments will be appreciated

On 2011-10-12 by (mod) - out side fan runs good but compressor does not

Tim, as your A/C compressor is not running you need some diagnosis and repair. It might be something minor like a starting capacitor, or a larger problem such as a burned out compressor motor.(links found at the INDEX to RELATED ARTICLES near the end of this page) see the article titled "Compressor Diagnosis: Diagnose & Repair" or search InspectAPedia with that phrase

On 2011-10-12 by Tim

out side fan runs good but compressor does not

On 2011-10-03 by (mod) -

Gary, see AIR CONDITIONER OPERATING TEMPERATURES (use the on page search box to find that article)

On 2011-10-03 by Gary Johnson

Is there a general expected temp required for a wall unit? Mobile home has a wall unit but it seems that the output temp is only cool not cold. How can I determine if unit is working properly?

On 2011-10-02 by Anonymous

thermostat stated low batteries. replaced batterie, but now refrigeration unit does not turn on

On 2011-09-07 by dan

What would cause my heater fan to turn on when it's not suppose to.

On 2011-09-07 by (mod) -

Paul I've considered your original question again with more care.

I'd start by making sure the blower fan will actually operate; have you checked the air handler to see if the fan starts. If it does not, after checking for voltage, lost drive belt (for indirect drive motors), see if you can run it directly - should be able to jump two TT wires.

If the fan runs and you have no air at registers there is a duct blockage or disconnect.

On 2011-09-06 by paul

hi dan, thx for the response. i forgot to mention i live in san diego. so, i think this unit probably doesn't have a backup heater.

i looked at the blower unit and the airbox/plenum and don't see anything that would indicate electric heating. the electrical conduit goes just to the fan blower.

i think the refrigerant has leaked out. i'm going to have an HVAC tech check the line for leaks and repair as needed and then recharge. what would a typical cost for this be? i'm not in a big hurry as it's not really hot or cold outside right now. thx.

On 2011-09-06 1 by Amie West

I appreciate any idea, thanks. I have checked all the connections for continuity, but calling the manufacturer is a good idea.

I hate to call a repair man for something that I could do myself, this is just so unusual that it is hard to diagnos. I'll let you know, but if anyone else reads this and has an idea, I'd love to hear it.

On 2011-09-06 by (mod) - fan controller problem

Amie sorry we're not smarter, maybe another reader with experience will chime in

. But it sounds as if you could have a fan controller problem; some A/C units include controls to vary the fan speed or even turn it off; or a wiring problem, even a loose connection; I'd review all of the wiring connections carefully for soundness and then perhaps give the manufacturer a call - for your unit model number a service department tech may know exactly what's happenbing.

Keep us posted - it'll help other readers;

On 2011-09-06 by Amie West

I have a package unit airconditioner. The circulating fan is failing to opperate at random times. In an attempt to solve the problem, I have replaced the contact switch and capacitor. The air filter is clean. I have taken the circulating fan motor out and had it bench tested.

It tested OK. The thermostat works normally. The air conditioner cools the house well during the times that it is not failing. The compressor fan continues to work at the times when the circulating fan fails. There seems to be no consistent reason for the failure, as in the outdoor temperature can be hot or cool, or the machine may work normally for only 2 hours or over 24 hours.

Can anyone tell me what the problem might be, or tell me what I should try next to solve this strange problem? Any help will be appreciated.

On 2011-09-06 by (mod) -

Paul often people leave something disconnected not out of malice but because it's not working properly and they just don't want to deal with it. I'm presuming you bought without a home inspection - else the inspector would have most likely tried turning on the system and you'd have had a warning about this repair.

Also foreclosed homes are often ones at which repairs and maintenance have been let go - people who are not paying on the mortgage are also not doing home repairs.

It's possible that a heater control board or actual heating elements have failed in your unit. Take a look at

BACKUP HEAT for HEAT PUMPS (in the INDEX to RELATED ARTICLES found at the end of this discussion) for help in diagnosing electric heaters that aren't working

On 2011-09-05 by paul

i have a central HVAC system, electric haet and AC. this is in a condo i bought. i found the wiring to the thermostat DISCONNECTED when i bought the place. i think the prior owner was upset about getting foreclosed on and decided to leave me a "present".

anyway, i looked at a neighbour's thermostat and wired it up exactly like hers. now, the fan comes on as it should and the AC compressor kicks on when i tell it to cool by setting the temp to lower than in the unit. HOWEVER, i get no cold air blowing! i also cannot get any hot air when i set the thermostat to go higher than room temp. the thermostat is a honeywell T8100C. does anyone have any ideas? thx!

On 2011-09-01 by (mod) - new compressor is not cooling as well as the old system


If your new compressor is not cooling as well as the old system did and the capacity was properly matched, I wonder if the refrigerant charge was correct? A check of the air temperature drop ACROSS THE COOLING COIL should find between 15 and 22 degF.

If you're seeing that temperature drop at the coil the A/C system is operating normally in all other respects (no dirty blower fan, good airflow, etc), then it seems possible that the too-hot conditions in the home could be due to weather, house heat gain, and adequacy of the whole A/C system to start with

On 2011-09-01 by (mod) - hard starting compressor


sounds like a hard starting compressor; ask the hvac tech about a start/run capacitor kit.

On 2011-09-01 by (mod) - AC unit trips breakers

Jeremy an A/ C unit that trips breakers is probably drawing too much current - a sign of a hard starting or seizing compressor. So what your tech says sounds credible. The price sounds low for New York and normal for some other areas.

On 2011-08-28 by Jeremy

We have a 3.5 ton condenser and he quoted me $1500 for just the compressor with a warranty of 6 months and recommended the entire condenser to be replaced since the warranty would last 5 years. Are the prices and what would be your suggestion?

On 2011-08-28 by Sarah - insufficient cooling

About a week ago we started noticing insufficient cooling of our 1000sq ft condo unit by our heat pump. We replaced a very dirty AC unit filter, and ran various checks as you recommended above. Later that same day, the temperature began steadily rising in our unit...the air was blowing but no cool air out of the vents at all.

We got opinions from two AC repair companies, both of whom said the compressor needed to be replaced. Luckily, the part was under warranty (the unit is only appx 3 yrs old and we are the first to live in it). It took a good 48 hours or so for the place to become cool again after the work was complete. And now, a week later, it still does not seem to be as cool as it should be.

Overnight, the temp drops as we want, but the AC seems to run all day. Tonight, for example, the thermostat has been set on 75 for the past 6 hours, the AC has not gone off in those 6 hours, and the thermostat still reads 79 degrees

. A thermometer in the vent reads 68 degrees. We are in central Texas, and the temperatures have been over 100 for 70+ days (110 today actually)...but I'm not sure that I should totally write this off as the reason for insufficient cooling. Am I just being paranoid, or should I assume there is still a problem?

On 2011-08-28 by Jeremy - compressor is completely shot.

My central air tripped the breakers and I swithched it back on. It worked for one night and tripped again the following morning. Now cold air wouldn't come out so I called a tech. He was testing the compressor with a booster(?) and a pop sounded and tripped the entire house of electricity. We had re set the main fuse box and he later said the compressor is completely shot.

We have a 3.5 ton condenser and he quoted me $1500 for just the compressor with a warranty of 6 months and recommended the entire condenser to be replaced since the warranty would last 5 years

On 2011-08-27 by Peter

My Ac wont cool. I have checked the filter and is clean. The air handler is clear. The air handler stays on and the out side unit will not come on the unit is 2 years old

I cut the power to switches and reset them. The out side unit came on for the night and now will not turn on. I push in the relay on the out side unit and he house starts to cool but when I let go it shuts off again

On 2011-08-26 by (mod) - Lost Cooling Capacity

Thomas I can't say you need a new unit before there has been an accurate diagnosis of the problem. When the outside compressor/condenser is not running you won't get cool air inside; but the problem could be a simple as a switch or control relay, or as serious and costly as a bad compressor.

Hot to touch sounds like a compressor motor that is not starting but I'm just guessing from so little info.

Under the LOST COOLING CAPACITY article (Found in INDEX to RELATED ARTICLES at our Continue Reading suggestions at the end of this article) you'll see a link to

Compressor Diagnosis: Diagnose & Repair

I'd take a look at that info as well as calling an HVACR service company. Keep us posted.

On 2011-08-26 by Thomas

The AC unit runs but no cool air and no fan running outside, the unit is very hot to the touch.

My Main central Air unit outside is very hot and the fan is not running but still running, The smaller unit is still running fine. I have two because my house is very big 3600 SqFt. Do I need to get a new Central air unit?

On 2011-08-25 by (mod) - sounds like a bad compressor or other motor


I'm sorry to say you needed to call an HVACR tech. It sounds like a bad compressor or other motor that has failed.

It could be an electrical short - a short circuit might trip the breaker but also burn the wire enough that when you turn power back on there is no actual electrical connection - the circuit has become "open".

On 2011-08-25 by (mod) - How do I look inside the air handler?


the Air Handler has removable covers; you may have to remove some machine screws; and of course turn off power first.


The evaporator coil is usually inside of the indoor air handler or blower unit. It won't be visible without removing equipment covers.

On 2011-08-22 by Jeff Huston

Have an 11 year old compressor/fan unit that kicked off the breakers and now will not run at all. Replaced the capacitor, still no soap, although it is not kicking off the breaker now. Checked the fan motor for a reset button, and there isn't one. Any suggestions short of calling the serviceman?

On 2011-08-22 by Ivan Emerson

How do you find the evaporator coil inside an apartment unit?

On 2011-08-19 by Marc - How do I look inside the air handler?

How do I look inside the air handler?
I do a "T" in the pipe leading away from the air handler that leads to the outside of the house where the condensate goes. If I open the top of the T, I do feel cold air rushing out from it. Don't forget, I'm in Houston, humidity is out of sight here. :-) 90% in the mornings outside, it is about 55% in the house. I'm so confused. So happy it is working, so worried that there is no water. Thanks for trying to work with me DanJoe.

On 2011-08-19 by (mod) -

Marc you can inspect the inside of the air handler unit where the cooling coil is located. If you see air blowing across the cooling coil, and air is being cooled, you'll see condensate on the coil and dripping into the condensate drip pan and from there draining to a disposal point. If none of that condensate is backing up, leaking, overflowing, you're ok.

The rate of condensate production is significantly determined by the relative humidity of the air being cooled. If the air RH in your home is already low, less condensate will be produced.

On 2011-08-19 by Marc

Three days later, all is still fine with the cooling. Not a drop of water from the outside line. I can't find any evidence that it is leaking elsewhere in my house. And it seems like I would by now since I was producing several buckets of water each day. Should I be worried?!

On 2011-08-18 by (mod) - zero condensate might be ok or there could be a clogged drain

Marc if your A/C is working and cooling adequately and zero condensate is appearing, your condensate drain or piping may be clogged. Bleach won't unclog a line.

On 2011-08-18 by Marc

Additional comment... 36+ hours now and counting, still no wate but the a/c is working fine, thank goodness

Last night I did pour some bleach into the pipe going directly from the box (with the coil inside?). It wasn't alot, maybe I need to add some more?

I'm so happy it is working but I am very concerned. Thank you. It is 100right now, supposed to get up to 104. Yuck.

Hi, I live in Houston TX (it's hot here!) and my hose leading to the outside of the house has been dripping quite steadily for months, sometimes nearly pouring. Now, as of this morning, I'm getting almost nothing. I have checked my overflow pan and it has some water in it but not enough to go in the hose.

Nothing seems different inside, the air is cold and it is shutting off and on and staying the correct temp depending on what we put on the thermostat.

Should I be worried? Is there a problem? What happened to all the water? I have been letting it drain into a bucket and watering the yard with it. We are in the worst drought in TX history. Thank you!

On 2011-08-17 by (mod) -

Craig you will want to review the LOST COOLING diagnostics (use the search box on our pages to find that article), and also your filter, air handler and duct system for blockages, leaks, mistakes. For that, see DUCT SYSTEM & DUCT DEFECTS (Found in INDEX to RELATED ARTICLES at our Continue Reading suggestions at the end of this article).
Keep us posted.

On 2011-08-17 by Craig

I've just moved into a house where there seems to be very little air flow from the ducted heating. Heating only occurs for a short period and then cool air seems to flow out. I had a service technician come out and he said the compressor is getting too hot a tripping out.

He said that maybe there is a problem with air flow or pressures.

To me it's obvious that there is at least an air flow problem so after he left I climbed into the roof and found that the ducting pipework does basically a 180 degree turn around a truss brace.

The ducting there almost seems to have collapsed in on itself. To me it seems clear that this is most likely be restricting the air flow. Would this in turn be causing the compressor to trip out?

On 2011-08-16 by (mod) -


you will want to read through the lost-cooling diagnostic suggestions above to have and idea why your A/C system is blowing hot air; a common cause is loss of refrigerant.


if your unit is a heat pump I wonder if it's running backwards - in heating rather than cooling mode. If it's not a heat pump and your inside lines (and coil) are icing up you may be low on refrigerant. In any case it sure sounds like a service call is needed.

On 2011-08-16 by patty

i think someone has messed with my air conditioner the inside lines started freezing up and the outside unit is blowing out cold air instead of warm can u tell me what culd have been done

On 2011-08-15 20:13:47.057133 by andy dacosta

why is my air co blowing hot air

On 2011-08-15 16:23:07.542312 by (mod) - Turning on the blower manually keeps it running

When you turn off your A/C and switch the fan to "ON" you are manually turning on the indoor blower assembly fan itself, independent of the A/C system.

On the thermostat if you set the appropriate switch to "COOL" that turns on your A/C system and the fan will run automatically under control of the thermostat and additional control circuits in the air handler and in concert with the outdoor compressor/condenser unit. Normally if a thermostat has the necessary switches and it's wired correctly, you could set the TT for COOL and ALSO set the fan either to AUTO or to ON. in "ON" position that forces the fan to run continuously regardless of whether or not the TT is calling for cooling.

But you're not seeing that.

When you turn on the A/C at the TT but you are not getting cooling, either a service or control switch is OFF at your equipment (or in the main electric panel) or a thermal overload reset switch has turned off the equipment, or a motor such as a compressor motor has seized.

I'd start by going through the LOST COOLING diagnostic steps starting at the top of this page to be sure everything is turned 'on', and if that doesn't help you probably need an HVAC tech service call.

On 2011-08-15 by clexow

my outside ac unit will turn on, but the fan inside will not blow air through the vents. but if I turn the ac to the off position, and the fan to "on" instead of auto, the fan will start blowing air. It is like I can either use the fan or use the ac unit, but not both of them

On 2011-08-15 14:51:44.375990 by (mod) -

If your outside compressor/condenser is not running it could be a bad capacitor (not a big repair) or a bad compressor (big repair). But the fact that the fan is not turning but you hear noise means you need to start with checking the fan motor and its start/run capacitor.

Watch out: when a condenser/compressor unit fan stops running, leaving the system ON and the compressor running can cause the compressor to overheat, experience high head pressures and thus lead to compressor damage. Turn off the system until it's diagnosed and fixed.

On 2011-08-15 by DON RAUTH

A/C not cooling; however, air is blowing through the ducts. Outside unit fan is not turning, but noise is coming from the unit. System is 20 years old. Based on what I read above sounds like it COULD be blower motor at outside unit or the capacitor. Any other words of of wisdom. If blower fan or capacitor, are these expensive repairs?? Thanks for your valued input.

On 2011-08-12 by TN-Goose

Dan: I just emailed you with the link to TEV (TXV) failure effect on the compressor.

On 2011-08-09 by (mod) - check & diagnose before replacing an air conditioner

Bill, before springing for a completely new air conditioning system, I'd ask for some diagnostics on the present one. Your old system might need simply a control replacement or a refrigerant leak repaired.

On 2011-08-09 by Bill in VA

My AC system stopped working this evening. The blower was still working but no cool air circulating.

I checked the outside system compressor/housing and found ice build up on the tube running from the compressor to the house.

The unit is almost 14 years old, and we've had nothing but 90+ temps for the past two months. Is it just time to purchase a new outside compressor unit and a new inside AC coil unit. My neighbor just replaced his at a cost of $7,700.

On 2011-08-08 by (mod) -

Checking the TEV:

a simple step that can tell something about the TEV (TXV in your lingo) is to just try warming it up with a hand or a hair blow-dryer. If the valve is frozen and it's warmed it'll start working.

Other tests involve using a gauge set and making adjustments to the valve while watching the frost line on the cooling coil. On occasion we might hear chattering at the TEV - an indication it's not working properly.

On 2011-08-08 by (mod) - Thermostatic Expansion Valve hunting.

Thanks TN for the note about Thermostatic Expansion Valve hunting.

The comment script used on these web pages won't allow any of us to input web addresses in the body of a comment (nor profanity).

If you'd be kind enough to email the information to me I will research and add a proper citation. Our email is(links found at the INDEX to RELATED ARTICLES near the end of this page) , top and bottom where you see the word



On 2011-08-08 by (mod) -

David, for diagnosing problems with the compressor/condenser fan, look at the articles(links found at the INDEX to RELATED ARTICLES near the end of this page)
FAN, COMPRESSOR/CONDENSER UNIT <---------- take a look at this article

On 2011-08-07 by david

things to check if the outside fan is not running on airconditioning. thanks!

On 2011-08-07 by Alan

my blower unit is 12000BTU and the outdoor
compressor is 9000BTU . the cooling
seems to come in waves. sometimes
its cold sometimes theres juz not much cool air. thanks for ur previous reply. very prompt.

On 2011-08-07 by TN-Goose

The text I showed ealier on TXV's effect on the compressor is not my words; so if you add them to your article, please give the proper credit to the source. I tried several times to input the website address of the source, but for some reason, this site won't let me input the address.

Any idea on how to check / diagnose the TXV (TEV)?

On 2011-08-07 by (mod) - superheat and hunting thermostatic expansion valve -

Thanks for that detail about superheat and hunting thermostatic expansion valve - I'll be sure the text is added to the TEV article.

In other words, an improper TEV setting can cause rapid opening/closing of the valve resulting in liquid refrigerant flooding the suction line, entering the compressor motor. Because compressor motor moving parts and valves are designed to compress a gas, and because a liquid (refrigerant) is not particularly compressible, the compressor motor, piston, crank, or more immediately its refrigerant valves are likely to be damaged or destroyed.

It is possible that dirt, debris, or even water in the refrigerant piping system and that enters the TEV could cause this malfunction by freezing the valve's moving parts.

And of course a seized compressor would be expected to trip the circuit breaker the next time it tries to turn on. The TEV didn't cause a short circuit but it could have damaged the compressor leading to an overcurrent and a tripped circuit breaker.

On 2011-08-06 by TN-Goose - information on the effect of TXV on compressor - Hunting

I found this information on the effect of TXV on compressor.

TXV superheat set too low:

The superheat must be allowed to change in order for the sensing bulb to make corresponding adjustments to the valve opening while it maintains the set superheat.

A low superheat setting can allow the superheat to fall to zero. This condition will cause the valve to close and the superheat will soon rise well above its setting.

This in turn can cause the valve to reopen wider than necessary and overshoot the superheat setting.

This condition is called hunting. On one of the valve's swings to the wide open position, liquid refrigerant can flood the suction line and allow liquid to enter the compressor, a potentially damaging condition.

On 2011-08-06 by (mod) -

A bad TEV can cause abnormal system pressures, including excessive high side pressure that one would hope would cause a safety control to stop the system.

But I don't know why it'd cause a short circuit - maybe. None of us knows it all, but that failure is not one we learned about in my HVAC classes.

On 2011-08-06 by TN-Goose

Can a faulty TXV (TEV) cause the compressor to short-out?



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