Heatpump cutting out every 20 seconds or so - any ideas?

[LeeH]

The compressor on our Carrier heatpump runs for about 20 seconds then cuts out for a split second... runs for another 20 seconds, then cuts out again. It only seems to do this in the hottest part of the day. It does it for a while then go back to normal operations. Any suggestions?

The compressor and run/start capacitor were replaced a couple of years ago when the old one died.

[futuresoptions]

Quite possibly a couple of things could be wrong...

For starters make sure the outside fan is running, if not, it is going into high head pressure.

Also if your outside coils are dirty this will cause the same thing.....

If you have a manual high pressure reset this will not be the problem..... the compressor would come on run 20secs and then drop off till you manually reset the pressure switch.

what it sound like to me is that you are low on refrigerant and the unit is cycling on and off from the low pressure switch. usually these do not have manual resets.

either way if and when you have a tech come out and look at the unit, tell them to install a 5 min time delay so that this short cycling does not continue in the future.... this will overheat your compressor and short it out internally from heat. if your compressor is internally protected it will eventually trip on internal overload and will take up to an hour or so to cool down before it will try to start again.... once this feature goes... you will be looking at a new compressor plus labor.....

hope this helps

[Por_sha911]

Overheating will cause it to cut off.
Low refrigerant.
Short in a wire (ask me how I know about this one).
+1 on having a tech come out but make sure he's honest or you may be buying a compressor when all you need is a new relay... If you get quoted for major parts cost, get a 2nd opinion (ask me how I know this too).

[futuresoptions]

If it's only doing it in the hottest part of the day, then it is probably going off on high head pressure.... and you do not have a manual reset, but an automatic reset...... I would kill power to the unit...varify that the power was off with multimeter... and clean the coils with a garden hose....... do not get water in the fan motor or any of the electrical..... return power when done and this should solve your problem. If it does not solve the problem, go outside when it is doing it and see if your fan stops running right before the compressor goes out..... this could be the fan or its capacitor giving up....... also if and when your unit is doing this listen for a loud click at the outside unit.... if you hear a loud click before the compressor shuts down it could be an electrical problem with your reversing valve....... just some more thoughts to ponder..... I believe I would start with cleaning the coils and 9 times out of ten this will solve your problem....... if it does my fee is $75. hr and I accept Paypal.....

[turbo6bar]

Cleaning the coils is a really good start.

[LeeH]

Originally Posted by futuresoptions

... my fee is $75. hr and I accept Paypal.....

I wouldn't mind paying your fee. It's the travel time that would kill me!

I appreciate the advice. I'll see if I can track down a good tech.

[futuresoptions]

No kidding, it would be a little high....LOL, whatever you do, do not allow that problem to persist or it will kill your compressor pretty quickly if not taken care of..... what happens is the motor is going on and off so much in a short period of time that the refrigerant hasn't equalized pressure and that thing is having to try and start under a load.... also it is going into higher than locked rotor amperage ratings over and over again in a very short period of time..... generates alot of heat and sucks alot of electricity.... get it cleaned and or repaired asap......

[onewhippedpuppy]

Saw it a few times where the main power relay/switch went bad. Many compressors have a contact switch, that physically moves to make contact and power the compressor. This switch is actuated by the signal from the thermostat. This switch physically moves, if you open up the electrical panel you can watch it. I believe the movement is due to an electromagnet. Regardless, the switch can go out. If you see the switch popping in and out, it may be a cheap and easy place to start. Local HVAC place can get you the part, kill the power to the unit and swap them out.

[Joeaksa]

Lee,

What did you find out on the A/C issue?

[Brian 162]

Does your condensor motor cut out as well? My guess is a loose connection or what the others have said. Check high head switch, or low ambient switch ( if you have one).
One thing I saw a few years ago was a compressor tripping out on the internal overload. I removed an insulating blanket that was around the compressor that reduced noise but re-tained heat. With the power off I hosed down the compresor to cool it off. I re-energized the unit and it was o/k. FWIW my company charges $125 per hour.

[Hugh R]

go to applianceguru.com its a bbs like pelican. They solved my dishwasher problem with me asking one question. If you want to search its free, to join is a one time lifetime fee through paypal of I think $5. Solved my icemaker problem as well. Its a deal.

[LeeH]

Originally Posted by Joeaksa

Lee,

What did you find out on the A/C issue?

I hosed down the coils. They were only slightly dusty and it didn't seem to change much. One thing I noticed is that after it runs a couple of cycles with the comressor cutting out it makes a sound - sort of like the compressor coming on... even though it's already on. Sort of hard to explain. Made me wonder if it was going into defrost mode. After it does whatever it's doing, it doesn't seem to cut out any more for some time.

Best I can tell the fan motor is not cutting out with the compressor. It's hard to tell as compressor is only off for a split seccond. If the old unit didn't rattle so bad I might not even notice.

[stomachmonkey]

No contribution here, clicked the thread cause I read Hemp pump. Sorry, long couple of weeks on the road. I'm tired.