My heat comes on and you can hear the condenser unit come on as well. However the fan is not turning? The outside temp is 30 degrees? Is this normal?

Can anyone share some wisdom on this? Thank you.

  • 1
    Is the heat working? Do you have multiple heat sources? Commented Dec 8, 2018 at 22:43
  • 2
    Can you share some model numbers and the brand?
    – Machavity
    Commented Dec 9, 2018 at 18:54
  • Those I have seen do not run the compressor below about 40 F, it has poor efficiency. They then use electric resistance coils . Commented Jan 30, 2020 at 22:33

1 Answer 1


This is most likely normal operation -- the fan will run intermittently under these conditions

Under low ambient conditions, the pressures and temperatures in an air conditioner or heat pump will go off-kilter, eventually to the point where the unit no longer functions due to a coil freezeup or worse yet, liquid refrigerant re-entering the compressor and killing it. In order to mitigate this, a properly configured heat pump (for most climates) will have some form of low ambient control that manipulates the heat pump's operating parameters to keep it going (and heating your house). (This is in addition to other accessories, such as a crankcase heater that keeps the oil from gumming up.)

One of the more common forms of low ambient control modulates (either on/off as on yours, or actual variable speed on more sophisticated units) the outdoor unit fan to allow the outdoor coil to run at the correct temperatures and pressures despite the dropping ambient temperature conditions. Hence, if you observe your outdoor unit for a while, you should see the fan on it cycle intermittently -- this is the low ambient control working.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.