# Compressor overheating



## eh75 (Jul 17, 2011)

My Lennox HP29-030-1P AC keeps shutting off the cooling and repairman is lost for answers. They've been out 5x's, pressures are normal. Some days the system will cool for 12 hours and other days under 2 hours. I;ll turn off system and let compressor cool and then it will turn back on. Techincan has never seen this problem. They called Lennox but they said they didnt know. Curious, can you replace the thermocoupler on the compressor (just a guess that's the problem)? What else could be wrong?


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## yuri (Nov 29, 2008)

There is no thermocoupler. Does the compressor get so hot that you cannot touch it? Has an internal overload inside but that usually takes 6 or more hours to reset. Did they check the capacitor to see if it is weak?


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## eh75 (Jul 17, 2011)

Yes the compressor get very hot. Technicain ran water from outside hose on it to cool off so he could work on it. Yes, the capacitor was weak and was replaced, plus they added a "start cap"...all meter reading and pressures seems right on. Note: the technician has not worked on system when is was not working since I had reset the system by the time they had arrived. I will not reset next time. One tech has 32 year experience and is clueless at this poiont. I keep worrying its the compressor that's going bad. Once it quits cooling the interior thermostat has to be turned to "off" position and I typicaly wait 30 minutes to turn back on (some days it may take 3+ hours fo the the sysytem to start cooling).


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## Doc Holliday (Mar 12, 2011)

yuri said:


> There is no thermocoupler. Does the compressor get so hot that you cannot touch it? Has an internal overload inside but that usually takes 6 or more hours to reset. Did they check the capacitor to see if it is weak?


If you run continuous water over the compressor from a garden hose, 15 minutes max.


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## yuri (Nov 29, 2008)

If it is overheating the condensor fan may be stopping in mid cycle but that usually blows the internal relief valve which sounds like a rifle being fired. If the fan is slowing down it may overheat the compressor. I don't do heat pumps but have heard that a faulty reversing valve can cause it to over heat??? Marty are you out there. We have some heatpump techs here.


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## eh75 (Jul 17, 2011)

Fan appears to be working fine. Any chance it could be my thermostat? I've been tracking the problem for the past week...based on ambient temps the system seems to quit cooling on days greater than 80 degrees but have found nights in the 70's affects the system similarily. The system always works (fan, blower) just the ac quits cooling. Last thought, the time it takes for thr sysytem to begin cooling again takes anywhere from 30 minutes to 4 hours. I have found the longer the I keep the thermostat in the "off" cooling positon (once the cooling stops) the longer the ac works once it turns back on.


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## yuri (Nov 29, 2008)

Thermostat is not the problem. Sounds like it is a cumulative effect/heat buildup in the windings of the compressor. Hang in here and maybe one of our heatpump guys will know about the reversing valve possibility.


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## JJboy (Oct 12, 2010)

You can test a reverse valve using a small magnet.


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## eh75 (Jul 17, 2011)

Thanks. I'll have them test tomorrow. AC been cooling great past 6 hours blowing out 55 degree air. Unfortunalely in a few minutes or hours out it will stop cooling. Thanks for all your help!


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## Nfanelly (Jul 17, 2011)

Did they check your pressures? Sounds like it could be a plugged condenser coil. It might not looked plugged, but dirt and cottonwood can get caught in between the fins causing the compressor to overheat and trip out on high head pressure.


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## Marty S. (Oct 31, 2009)

If everything works right when he's there then I'd suggest concentrating on the txv . Ask what the superheat is when they come out next time.


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## KAVF (Aug 12, 2009)

By resetting the outdoor unit you can be clearing any fault codes that can assist the technician. If your unit has a high pressure switch that should be keeping the compressor from shutting off that way. If it has a high pressure switch but is still shutting off by thermal cut off it would most likely be due to not enough superheat keeping compressor cool. If problem persist and you dont have a high presssure switch maybe one could be installed on the defrost board and this would help in diagnostics.


KAVF


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## eh75 (Jul 17, 2011)

Manufacturer rep came out today to tell me compressor is dying. It appears my capacitor instead of failing continued to provide low power to the compressor for at least past 6 months most likely wearing out compressor. Having high 90 degree weather and compressor hots overlead and stops cooling aobut every hour for 5-10 minutes.

Question, this system is 10 years old...new system is $6000-6500 and new compressor $1600. Cash poor right now and thinking of just replacing compressor hoping AC will work for at least the next few years. Am I wrong to replace just compressor?


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## yuri (Nov 29, 2008)

I would get the compressor replaced and that is a reasonable price. Some Lennox units had 10 year warranty on compressors and some had 5. Did they check. If you have the owners manual and papers it should be at the back of them. Post the serial # and I can give you the date of manufacture. They will give you 6 months past it if you have no bill of sale.


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## JJboy (Oct 12, 2010)

If the general condition of the AC is good ( evap coil, Condenser coil, funrnace ) you have more than 10 years.


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## eh75 (Jul 17, 2011)

You've been very helpful...thank you.


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## yuri (Nov 29, 2008)

reread my post I added to it. compressor may have a warranty.


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## eh75 (Jul 17, 2011)

Thanks...It's a Lennox with a 5 year warranty.


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## yuri (Nov 29, 2008)

I found the owners manual on Davenet and it has a 10 yr limited warranty on the compressor and 5 on parts. Unless it was marketed or sold differently in your area. Cannot post the link as it is blocked for out of production units. Post the serial #. Talk to the district manager if necessary.


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## eh75 (Jul 17, 2011)

Compressor serial number......

Model #.....HP 29-030-1P

Serial #.....5801J32561

Thanks!


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## yuri (Nov 29, 2008)

2001 a= jan b=feb c=mar d=apr e=may f=june j=july. Made in July 2001. shipped in July or later. not likely you got one that fresh off the production line so you should be OK. you will have to pay for the labor and a new capacitor and I would fight with them about it if they won't do it under the compressor warranty. there is a district manager and check the website lennox.com for a 1-800 contact us. ONLY do that as a LAST resort. if you are reasonable/non belligerent the dealer should take care of you. there were some that were sold cheaper and may have a 5 yr warranty but I highly doubt it. depends on the local area but Lennox from all the years I have dealt them does not try to weasel out of a warranty.


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## yuri (Nov 29, 2008)

eh75 said:


> Compressor serial number......
> 
> Model #.....HP 29-030-1P
> 
> ...



......


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