Heat pumps often don’t work well during extremely cold weather. This article discusses how to fix cold-weather heat pump problems. This is a collection of questions we’ve received at HomeTips, along with the answers we’ve offered.

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Please note, be sure to see our article, Heat Pump Troubleshooting & Repair.

Winter icicles hanging on a roof.
Heat pumps have a hard time generating heat in extremely cold weather. ©Don Vandervort, HomeTips

Heat Pump Not Heating

Brenda: We have a heat pump with our AC unit. It works fine until the temperature drops outside. The temp outside is now 11 degrees and no heat at all will come out. It just blows cold air. We have cut it off, left it off for an hour or so, turn it back on and all that comes out is cold air. Can you advise the problem?

Richard: I just bought a house that has gas heat with heat pump. I have always had an electric heat pump. Will the outside unit function when the temperature is below 40 degrees? I noticed it hasn’t been running. Is this a problem?


Don V. Answer: In general, heat pumps can be poor at heating when outside temperatures get really cold. Following is an article on another site that discusses this.

Then again, any of several components could be malfunctioning. It may pay to have a pro come out and check your system. You can get bids from local pros through this free online service: a heat pump repair technician.

Heat Pump Outside Unit Doesn’t Come On

Jimmy: I’ve bought a home and it has a 7 year old Bryant Heat pump/Gas furnace combination unit. We have only lived here 1 month. The home heats fine, but I did notice at late last night that the outside unit looked like it only ran for a few minuets. I got up twice later in the night and the furnace was running on gas and the unit outside was not running. In other words, the gas side had kicked in as needed.

Should the outside unit ever come on when temp is below say freezing? Last night it was 10 degrees here in IN. When we had warmer days, say 35 or warmer, the unit did run outside. When the heat pump runs outside it is rather quiet for a 3 ton unit.

Should I be concerned that the unit ever comes on when temp is so cold or is it just trying to cycle and then it realizes it is too cold so it stays then shut off until outside temp recovers above freezing or in the 30’s??

Don V. Answer: Though the unit may need servicing, I think your speculation at the end of your question is right on target. I’m guessing that the outside temperature is so cold that the auxiliary heat is doing all of the work. Unfortunately, this is not very efficient—heat pumps are not at their best in super cold weather.


Heat Pump Is Frozen

Bettina: Hello, My Heat Pump unit outside is frozen and has a thick block of ice on it. I have turned my unit off. What can I do to thaw out the unit outside?


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About Don Vandervort
Don Vandervort has developed his expertise for more than 30 years as a remodeler and builder, Building Editor for Sunset Books, Senior Editor at Home Magazine, author of more than 30 home improvement books, and writer of countless magazine articles. He appeared for 3 seasons on HGTV’s “The Fix,” and served as MSN’s home expert for several years. Don founded HomeTips in 1996. Read more about Don Vandervort