FAQs on air conditioner or heat pump compressor burn-out diagnosis & repair.

This air conditioning repair article series discusses the how to diagnose and replace a burned out air conditioner compressor.

Diagnose a Burned-Out Air Conditioning Compressor

These questions and answers about diagnosing and fixing a burned-out compressor motor in an air conditioner or heat pump were posted originally at BURNED-OUT COMPRESSOR - be sure to see the advice given in that article.

On 2018-01-18 by (mod) - jammed thermostatic expansion valve can cause coil icing or freezing

A TEV can jam from dirt and debris or other contaminants including moisture that can actually freeze in a TEV. It's not a part you can change out yourself.

On 2018-01-18 by Dan

By you Saying Frozen I'm Assuming you Meaning by that Seized Up or do you Mean 410 refrigerant froze up in Compressor and Valves?

Service Techs are Exactly Why my Unit is Messed Up High Prices and Shotty Repair Work and Parts Changers when the Parts were not even Bad most of the time.

On 2018-01-18 by (mod) - the compressor that will draw high amps, moreso if frozen or failed.

Dan

Indeed it's the compressor that will draw high amps, moreso if frozen or failed.

Besides a stuck or frozen TEV or a failed compressor motor or bad start capacitor, sure there are other possible causes - not all of which fit in a brief e-text.

Your service tech might also look for a failed heating coil on the compressor motor or a bad control board that is not running the heat pump through a required defrost cycle.

On 2018-01-18 by Dan

I Meant Quick Update on my Previous Comment several minutes Ago..

Quick I disabled the Compressor Wiring on Outside Unit and Turned Thermostat up to Call for Heat and the Condenser Fan is Working and DID Not Trip Breaker with Compressor Disabled So its Not the Condenser Fan.

I've had Heat as the Air Handler I'm guessing went into Emergency Heat Mode with Out Compressor or Outside Unit Functioning. Do you have any Other Advice that Could be the Problem besides the TEV or Compressor Being Burnt Out (Short to Ground)?

On 2018-01-18 by (mod) -

Dan you need an onsite service technician. The TEV, probably located in your air handler near the cooling coil, is not homeowner-serviceable. You can read about that device at https://inspectapedia.com/aircond/Thermostatic_Expansion_Valve.php

On 2018-01-18 by Dan

Where is Location of TEV on my Trane Unit is there Way for me to Check the Valve. Also Would it be Common for Bad Condenser Fan to Possible Cause the Draw of Amperage to Trip Breaker in Seconds?

On 2018-01-18 by (mod) -

Dan

If the TEV (Thermostatic Expansion Valve) that regulates the flow of refrigerant from the compressor high side to the cooling coil (low side) jams or freezes it stops releasing refrigerant and the high side pressures climb and remain there.

On 2018-01-18 by (mod) -

Adding reader comments received by email

milton silva
12/26/17
I have a 3 ton R22 rooftop heating/cooling home HVAC system failure (no heat right now). AC mechanic says compression ratio is 1:1 (should be 3:1 or 4:1) and AMP draw is 5.5 rather than required 20. Says compressor is bad and should be replaced. Any comment?

Reply:

If the AC compressor isn't compressing, the problem is typically internal, a worn compressor piston or a failed valve. As your compressor is typically a sealed unit, repair isn't feasible. The unit gets replaced. But before replacing the compressor, ask the tech if she checked the expansion valve. An expansion valve that sticks wide open will also give low compression ratios, lower current draw. That can be also an effect of refrigerant overcharge.

On 2018-01-18 by Dan

Last reply was from me in regards to your resonse pertaining to Srart - Run Caps and The TEV..

On 2018-01-18 by Anonymous

Start - Run Capacitor is New as I keep several on Hand Always same as Contact Relay Switches and Fan Capacitors Also. Whats a Frozen TEV? where is it Located on Unit?

On 2018-01-18 by (mod) - Trane XL 14i Model # 4TWX4036A1000A compressor not running

More likely the compressor motor is seized. A tech would probably measure the current draw on that circuit to confirm the problem.

Other tricky failures that can mimic a burned out compressor (and also actually cause that failure) include a bad start/run capacitor or a compressor that can't start because it's pumping against abnormally high head pressure, perhaps because of a frozen TEV

On 2018-01-18 by Dan

I have a Trane XL 14i Model # 4TWX4036A1000A several days ago when I got back home noticed the inside Air Handler was running but the outside Condenser - Compressor was not running or cycling at All. I checked the breaker and breaker for outside was tripped so I rest breaker and it tripped again within 2-3 seconds.

So I went outside opened up the unit to start troubleshooting the possible problem checking capacitor and contactor relay switch and looking for burnt or bad connection everything looked good. I even replaced the 40amp breaker in main breaker panel and then verified I had power from main breaker panel to outside disconnect and all was proper voltage.

I checked condenser fan it it spun freely. I only have low voltage going to outside unit from air handler breaker as the air handler is still working, I bypassed the outside disconnect and wired directly to make sure there was not back connection in disconnect, reset breaker and tripped in seconds again.

Could the Condenser Fan cause this Problem even if Manually it spins freely as I have not removed as of yet to troubleshoot fan or is it looking like my compressor is burnt out or something else I could look into for possible cause of Problem.

I have had Hard Start on Unit for the last 6 months to help prolong life of Compressor and light on Control - Frost Board is on and Flashing per Normal 1 blink every 2-3 seconds no rapid blinking. Any advise or Help would be Greatly Appreciated as I'm Hopling Compressor in not Burnt...

On 2018-01-15 by (mod) -

I don't know, Erica, I Perhaps it is because there is a refrigerant type change. For example R22 is now considered obsolete and changing the compressor might lead the installer to want to change the evaporator coil in the air handler inside

On 2018-01-15 by erica potter

If the compressor has burnt out on LG outside unit for ducted aircon why am I being asked to install a brand new ducted air con system instead of just replacing the compressor.

Apparently two pipes were touch to heat up.

On 2017-05-29 by Tony

I had a compressor that would run and pressure seemed normal but the suction line is getting hot. It isn't a heat pump so no reversing valve.

Landscapers hit low voltage wire and I believe short cycled the compressor for two days before I got to it.

i checked and had continuity through all three common run and start. But I had power coming out of compressor at start terminal. Therefore powering capacitor with 240 at herm terminal on capacitor. Any ideas why this would happen. I've never seen this before

On 2017-04-29 by (mod) -

Perhaps not, but I'm confused; you said the motor was drawing LRA - I assumed (oops) that meant it was not running and that it was drawing higher than normal running amps. Let's not mix up LRA and RLA - lock-rotor-amps vs running-load-amps.

On 2017-04-29 by Jank

RLA for compressor is 13.44 i checked while running and it shows only 4.4 amp , is it compressor broke ?

On 2017-04-29 by (mod) -

Typically that's a seized motor or bearing, right?

On 2017-04-29 by Darrell

Compressor is pulling lock rotor amps,than the amps drop back to zero on the meter.Is the compressor locked up?. Everything else checks out.

On 2017-01-24 by John

if a air conditioning system has three compressors and one has a burn out ,would you change the one or would you change them all

On 2016-09-30 by (mod) -

Barry my OPINION is that - it depends - on how bad the refrigerant piping seems. Typically when a compressor is replaced the installer places a burnout filter-drier or two on the system piping and might even return to replace them after some period, thus protecting the new compressor as well as the expansion valve from debris.

On 2016-09-30 19:01:03.306563 by Barry

Do you have to replace your copper pipe when your compressor burns out or can you use chemicals to clean out the copper piping?

On 2016-09-29 by (mod) -

Sounds like unsafe electrical wiring in the backup heating components. I'd be sure everything is turned OFF immediately to avoid a shock and fire hazard. Then review the wiring and connections and controls.

On 2016-09-28 by john

Trouble shooting a ptac system, put into heat mode sparks start,
Coolingbtu/HR 11700/11500
,heat 11300/11100
Electric heat watts 3400/2780
Electrical amp 15

On 2016-08-29 by (mod) -

Could be a bad relay or control board; your tech will also check the current draw at the compressor to check for a burned-out compressor motor.

On 2016-08-28 by Brian

Replaced capacitor have power to fan,compressor and power coming in and out of contractor. Still outside unit not coming on.

On 2016-07-12 by (mod) -

True that if a motor is failing, replacing the capacitor won't repair that trouble.

On 2016-07-12 by Calvin jeter

Had a new capacitor put in but compressor runs for a while then stops then after a while it starts back that's during the day fan still runs the whole time but at night it runs to its satisfied

On 2016-07-10 by (mod) -

Opinion is that you looked at the outside unit but the problem is the inside air handler unit; it could be as simple as a blower door interlock switch that's keeping the system off; check that it has power

. Search InspectApedia for AIR CONDITIONER NOT WORKING to see more detailed diagnostic steps.

On 2016-07-09 by Jill Strehl

A/C unit does not come on inside at all. I go outside and check unit - the motor fan is running fine. Inside filters (2) are clean. Just no airflow. Outside motor fan runs like a champ. I turned it off inside, to not just run the motor outside for no reason. Opinion?

On 2016-05-20 by arich

very nice article. thankyou its much helpful

On 2016-04-22 by dan h

very helpful thanx

On 2013-02-14 by Walter

My cheap MIDEA A/C turns on and is coolong but the fan doensn't blow air as before, when new it use to noow air at high speed but now it's like 10% blowing power.

On 2013-02-09 by Bruce

I have a tempstar 5 ton unit and a few weeks ago noticed my heat pump outside was not running . I checked the breaker in the house and it had kicked so I turned my thermostat off and reset the breaker

. Upon turning it on it kicked the breaker again. I went to the heat pump and removed the cover and to my surprize had a mouse tangled in the wires by the start compacitor and had built a nest. I removed it and thought maybe it had grounded something.

Well i turned the unit back on and kicked the breaker again. Is this my compressor or possibly done something to the start compacitor. I need help. lol

On 2013-02-01 by John C. of Central Coast Califor

I'm in a rental home, approx 2,000sqft (18,000 cuft), a/c and heating system have caused an abnormaly high electric bill when compared to homes with similar system and size in our area. Landlord sent tech, tech found disconnected intake duct, and partially connected output to register duct, repaired that (actually lowered the overall electrical usage, but still 2x above normal for our area). Tech also found a circuit breaker (a secondary service breaker located on the unit is how he described it), was "bad" and removed it from the system but was not allowed by the landlord to replace it so he "bypassed' it.

Now that the winter is here, the compressor/condenser unit outside comes on when the heat is running. My experience is that the compressor/condenser fan unit outside isn't supposed to come on when using the heat cycle. Is this correct even in an electric heat system, and what needs to done to fix it?

On 2013-01-28 by john

just replaced a-coil and compressor, and my pressure on both low and side are around 100 psi and the out-door temperature is around 32 degrees compressor is make small chattering noise. what's wrong

On 2013-01-27 07:02:15.738369 by Roberta

My evaporative air con is only 3 years old, and will now not turn on, what could it be?

On 2013-01-22 by Tony

I have a ducted split system. It always starts ok and blows cool air, however when it reaches the set temperature and stops, and then tries to start up again (so the control panel shows cool and run) the inside fan blows warm air. When I check the outside fan it is not working

. If I turn the a/c off at the inside control panel for 5 minutes and turn it back on it will work ok - I generally set the temp really low so it doesnt stop andn start a new cycle to prevent this.

On 2013-01-08 by Jim

trane XL13C package unit - the blower motor is vibrating like crazy, walls and windows rattle... I can spin the squirrel cage fan and its smooth, but when under power its really bad... I need a pdf on how to remove the blower assembly to replace the motor... anyone got one out there?

On 2012-12-18 by 100% Disabled Veteran

My dad was to, you made the right choice, but
it sounds like they put R22 back in a R410A system.
Semper FI.

On 2012-12-14 by (mod) -

Nick, we won't know what needs to be replaced without some investigation.

If a wire or control shorted out those can be repaired or replaced. But if the short circuit or blown fuse occurred because of a seized compressor or motor, that too will need replacement. A service tech will check the circuit, wirinr, and components to sort out the problem.

On 2012-12-14 by Nicki

I turned on our central heat and it wouldn't power on. I checked the inside breakers and found that the baker had flipped off. I switched it back on and again it flipped off. I then checked what I believe is the A/C Switch Fuse on the outside of the house (a double wide mobile home), the inside of this fuse box looks to be burnt black and has an odor of burnt wires. I then proceeded to turn of ALL breakers to the unit. My question is: Can we replace just the Switch Fuse or do we need to replace the entire system?

On 2012-11-30 by Found oil inside a pipe

I have LG HS-C096A4B4 1HP, have been using for 2 years by housemate and was clogged by dust badly (never been cleaned). Now the aircon is moved to my room, during evacuation, I found an amount of oil (no color) inside low pressure pipe. However after evacuation, the aircon is running properly. compressor amp reading is 3.6-3.8 instead of 4.1amps. I'm just curious where does the oil comes from. Is it a sign of burned/damaged compressor? TQ

On 2012-11-09 by (mod) -

Also see our inf on seized AC compressors

On 2012-11-09 by (mod) -

Andrea,

That sounds like perhaps a double hazard

A short circuit or bad connection at the switch and perhaps a fusenor circuit breaker that should have interrupted and turned off the circuit.

Check further for

A bad circuit breaker - see Federal Pacific Electric Stab lok info and also see aluminum wiring information both at InspectAPedia for examples.

On 2012-11-09 02:09:56.226330 by Andrea

What would cause the air handler power switch to melt? Last night, everything working fine...this morning, nothing that has to do with the heating/air will turn on, not even the thermostat on the wall...went to check attic, noticed a burnt plastic smell and saw the power switch was melted - outside fuse ok. Any ideas or suggestions? Thanks

On 2012-10-04 by Rhonda King rking@sbcglobal.net

I have a Ao smith fan motor 840 1/6 208-230 v fr 48Y that me and my husband were told went out. so instead of getting the same brand we went with a TRANE . It worked for a while then got hot and fan stopped cooled down compressor with water slowely not to get anything else wet. then inside air got real cold but fan got hot and went off again. what could it be.

On 2012-09-11 by Dan

What could cause the 60amp breaker to overheat and melt the contacts to the AC.. I've replaced the capacitors put in a new fan motor and the disconnect has been replaced in the past three years I changes out the 50amp cartridge fuses which tested fine no shorts .. I have a rheem 2.5 ton that operates on 230v its an older unit but still runs the compressor hasn't locked up so I'm just curious as what else could be going on here... the wiring for the unit is the correct gage pretty thick wires .. not sure if its the bus or the ac causing the issue..

On 2012-09-06 by (mod) -

Donna,

I'm not sure of course, with so little data, but it sounds as if your system may be stuck or sticking in "heating" mode - or has a bad control circuit or board. It's worth a service call by a professional.

Nanny:

Don't confuse condensate disposal - getting rid of the water condensate produced by your cooling system as it cools and dehumidifies buiding air - with refrigerant. And "refilling refrigerant" suggests another mistake. Refrigerant in an air conditioner is not something that gets "used up" - needing a "refill" - rather, it should never need addition except when the system has developed a leak. In that case it's best to find and fix the leak rather than to just continue adding refrigerant.

The condensate tray should never be "filled" - it's supposed to drain. If it's filled the drain is clogged and needs repair.

And yes, if the compressor were not running there would be no cooling in the system so the system indoor air handler would typically stop producing condensate.

But absence of water (condensate) is not along evidence of a bad compressor. The rate of condensate production depends also on the humidity level of indoor air and the amount of time that the A/C system is running.

On 2012-09-06 by donna

i have a 23 year old coleman heat and air unit ,,,the pasr few months powe bill is going way higher than ever for this time of year ,had unit checked out in summer ,,all seemed ok ,,,but now the weather has cooled of my unit comes on for a few minutes ,then kickes off ,,and on and off i keep inside thermostat on 72 ,,but my unit is on and off on and off always ..what could be wrong my power bill is getting way to high ,,,

On 2012-09-05 by Nanny

Our compressor died 2 days ago. Technician replaced capacitor but that didn't fixed the unit. They suggested replacing the A/C unit. We just had another technician done a maintenance service on the unit and refilled refrigerant about 3 weeks ago. Would the pan be filled of water if the compressor stop functioning? To me this doesn't make sense. :-( And how long would it take for the water in the pan to dry if the unit is in the attic and it's been 90-100s degrees outside? Could the technician have known that the compressor was going bad based on the absence of water? Thanks in advance!

On 2012-09-04 by Rob

compressor fan not running, replaced bad run cap, now as soon as the fan starts the coil for the contactor drops out and unit stops, runs and sounds fine if I hold in the contactor, what could be dropping out the contactor?

On 2012-09-02 by Jordan

My wife and I came home from vacation and our A/C wasn't working. We also noticed that the water to our home must have been shut off at some point during our vacation as all the faucets had air in the lines. The air conditioner blower is running inside the house and the compressor fan is running outside the house.

The thermostat is set to cool but only lukewarm air comes out of the vents. It looks like a water line runs from our hot water heater intake to the the A/C compressor outside. If the water was shut off, would this cause the A/C compressor/condenser to overheat and burn out?

On 2012-08-30 by (mod) -

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

On 2012-08-29 by Mohamed al lababidi

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,

On 2011-08-11 by free

good

...

Continue reading at BURNED-OUT COMPRESSOR - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• CAPACITORS for HARD STARTING MOTORS
• COMPRESSOR / CONDENSER REPAIR - home
  • AIR VELOCITY RATES TYPICAL FPM
  • BURNED-OUT COMPRESSOR
  • BASIC DIAGNOSTIC CLUES for BURNED OUT HVACVR Compressor Motor
  • BASIC ELECTRICAL TESTS for BURNED OUT COMPRESSOR MOTORS
  • COMPRESSOR FAILURES: OTHER CAUSES
  • COMPRESSOR REPLACEMENT, WHEN TO
  • CAUSES of HVACR COMPRESSOR MOTOR FAILURES
  • CAPACITORS for HARD STARTING MOTORS
  • COMPRESSOR / CONDENSER DIAGNOSTICS
  • COMPRESSOR / CONDENSER INSPECTION CHECKLIST
  • COMPRESSOR / CONDENSER INSTALLATION ERRORS
  • COMPRESSOR / CONDENSER LEVELING REQUIREMENTS
  • COMPRESSOR CONDENSER NOISES
  • COMPRESSOR MOTOR INSULATION
  • COMPRESSOR MOTOR REPLACEMENT
  • CONDENSING COIL REPAIR REPLACE
  • CONTACTOR RELAY DIAGNOSIS & REPAIR
  • CONTROL CIRCUIT BOARD, A/C
  • COPELAND ELECTRICAL HANDBOOK [PDF]
  • CRANKCASE HEATERS
  • ELECTRIC MOTOR DIAGNOSTIC GUIDE
  • FAN, COMPRESSOR / CONDENSER UNIT
  • FAN NOISES HVAC
  • HARD STARTING COMPRESSOR MOTORS
  • HEAT PUMP OUTDOOR UNIT DEFROST CYCLE
  • LONG-ON CYCLING AC COMPRESSOR
  • MOTOR OVERLOAD RESET SWITCH
  • NOISES, HVAC SYSTEM DIAGNOSIS - home
  • NOISES, HVAC SOUND DESCRIPTIONS
  • REFRIGERANT FLOODBACK, LIQUID SLUGGING
  • REFRIGERANT LEAK REPAIR
  • REFRIGERANT PRESSURE CONTROLS & SWITCHES
  • REFRIGERANT PRESSURE READINGS & CHARTS
  • SHORT CYCLING AC COMPRESSOR
  • TIGHT or SEIZED AC COMPRESSORS

Suggested citation for this web page

BURNED-OUT COMPRESSOR FAQS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to AIR CONDITIONING & HEAT PUMPS

Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia

Ask a Question or Search InspectApedia

Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Note: appearance of your Comment below may be delayed: if your comment contains an image, photograph, web link, or text that looks to the software as if it might be a web link, your posting will appear after it has been approved by a moderator. Apologies for the delay.

Only one image can be added per comment but you can post as many comments, and therefore images, as you like.
You will not receive a notification when a response to your question has been posted.
Please bookmark this page to make it easy for you to check back for our response.
Our Comment Box is provided by Countable Web Productions countable.ca

Citations & References

In addition to any citations in the article above, a full list is available on request.

---

ADVERTISEMENT

---