we have an attic heat pump with an outside compressor/condensor unit that is used for the second floor. And, we also have a separate air conditioning (a/c) with and outside compressor unit that is used for the main floor. The first floor a/c is working great; however, the upstairs heat pump is not working so well. We have both units serviced annually in May/June. Both unit checked good at that time. This summer in Virginia and recently we've had above normal humidity for this area with some days reaching a heat index (temp plus humidity) of 105 to 110 degrees. Now, that the heat subsided to an average normal 80 to 85 degrees in temp with moderate or normal humidity, yesterday, the heat pump was not cooling the upstairs. After looking inside the heat pump and inspecting the lines to the outside condensor, I found the entire heat pump coils and line leading to the outside unit completely frozen though the heat pump motor fan was continuous running. What could have caused this? Since the units were serviced about 3 to months ago, could the problem be just the environment working the unit hard; and shutting the unit down/off to allow the system to defrost cure this problem? Or, could there be a problem with the defrost cycle control? If possible, is this located outside on the condensor unit? If not possible, what do you think?

 

1st off turn your stats cooling selector to off and turn the fan switch to on. Let it run like this for a few hours to thaw it out. While it's thawing check your air filter and make sure it's clean. If not replace it and also check to make sure the outdoor unit has shut down.

A freezing coil in cooling mode is usually due to lack of airflow from a dirty filter or dirty indoor coil or low refrigerant charge. If the outdoor unit is still running even though you have the stats cooling selector to off then you may have a stuck contactot and that will need replaced.

Post back with your findings.

 

Kool-Aid,

Thank you very much for your expertise. Your approach worked perfectly! After thawing the attic heat pump coils, I tested the contactor and it works and functions properly. Now, I have switch the selector back to cool. And, for now, it seems to be generating cooler air; but, I will keep an eye on the refrigerant lines. I assume when refer to checking the air filter that you are referring to the large [20x20] return air filters located in the ceiling? I asked this because I did not readily see any type of filter in the heat pump unit itself. Though, it been recently service, I contacted our local service tech and he will be coming to check for low refrigerant and inspect for other related possible problems. Again, thanks...You were a big help and time saver!!!

 

If it freezes up again try not to operate it like this. A frozen unit will cause damage to the compressor.

 

If it does freeze up again, should I just shut the system down and then call the local service tech to prevent any possible damage to the compressor?

 

like Matt said if you see any frost on the llines turn the Ac off . Can turn tstat to fan on and let it run. If little copper line is not warm or hot and big copper line cold and wet at the outdoor unit and it is running . Id turn it off.

ED

 

Yesterday, when the local service tech came out, he discovered small (pin-hole) leak on the low pressure side that caused the problem. After fixing the leak problem, he only had to replace just over a pound of refrigerant, Since, we just had it serviced in June, and the issue was immediate noticed, the problem was corrected early. Also, I found out that our Goodman heat pump has an automatic cutoff switch in the condensor/compressor when the refrigerant gets to a certain low point it shut down to avoid damage to the unit.

I would like thank everyone on this thread for their expertise, advice, and especially your time. Keep up the great work!!

 

Also, I found out that our Goodman heat pump has an automatic cutoff switch in the condensor/compressor when the refrigerant gets to a certain low point it shut down to avoid damage to the unit.

Id think if it did have this on it that it could not ice up. Also he did put a new drier in the line I hope. Did you see him fix a leak??????

ED