This article is a collection of questions about cold-weather heat pump problems that we’ve received at HomeTips, along with the answers we’ve offered. 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: In general, heat pumps can be poor at heating when outside temperatures get really cold. Here is an article on another site that discusses this: Heat Pump Effectiveness In Cold Weather 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. 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: 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.how much to install air conditioning unit Bettina: Hello, My Heat Pump unit outside is frozen and has a thick block of ice on it. outside ac unit problemsI have turned my unit off. the ac unit is not coolingWhat can I do to thaw out the unit outside? Don V: It isn’t unusual for a heat pump to freeze up in cold weather, but it should kick into “defrost” mode and melt the ice periodically. Here are some conversations on other sites that might be helpful. Be sure to read the second one after you read the first one. A Frozen Heat Pump Is Normal

What To Do If Heat Pump Is Frozen More About Frozen Heat Pumps Roy: I have a standard “air source” type heat pump. It’s only a year old so it’s in great working order. Living in Michigan it gets well below 32 degrees in the winter. Is it wise or not to run it at such cold temperatures. Or should I stick with $2.00/gal.propane? Don V: In general, heat pumps —both gas and electric—can be poor at heating when outside temperatures get really cold. Here is an article on another site that discusses this: Heat Pumps and Cold Weather If the auxiliary heat has to kick on, it uses electricity to heat your home—and that gets very pricey. $2 propane as a heat source is probably much more affordable. Nikko: We have a heat pump that has trouble heating the house below about 40 degrees. Right now the temperature is below freezing and the house is more than ten degrees colder than outside, even with auxiliary heat on. We paid to have the ducts and coils cleaned, and it helped but did not fix the problem.

We looked at our ducts as best we were able and noticed that the system is pulling air from BETWEEN our basement ceiling and ground level floor. There is a big opening, about 1.5 ft2. Should we close it off? There is a normal register on the first floor (but not heated basement level) that is also pulling air. Don V: If I understand your description, the return-air is traveling in a chase between the ceiling and floor above it. Sometimes return-air ducts are designed that way—no actual metal duct, but rather a boxed-in chase. That’s okay, because it’s just drawing room air back to the heating appliance through that chase. You wouldn’t want to deliver heated or cooled air to rooms through a chase, however (too much heat loss). In general, heat pumps can be poor at heating when outside temperatures get really cold. Do heat pumps make sense with Minnesota winters? Also, can they be used with a radiator heating system? Don V: Typical air-source heat pumps are not normally used for radiant heating systems, but ground-source heat pumps are.

In general, heat pumps can be problematic in really cold climates. Here are a couple of discussions about this on two other sites: Heat Pumps In Cold Weather Discussion #1 Heat Pumps In Cold Weather Discussion #21. Any ice must be MELTED completely before trying these steps. Ice melts fastest in the A/C's FAN ONLY mode, (if the fan is catching in the ice turn your AC OFF!!) or you can use a hair dryer or additional fan as well. First let's look at a few easy potential solutions to your ice up: Dirty fins drastically decrease your cooling power and waste electricity! Clean them once every 1- 2 weeks. Use a brush with stiff plastic bristles that are 2" long to wipe down the fins. Rinse the brush in a pail of water after each swipe. If your fins were knocked and have become “squished” the cooling power will be decreased - use your fingernails or a kitchen knife to straighten them If it has been a very long time in between cleanings, they make a special foaming coil cleaner for air conditioners.

It costs about $5-7 and is available at hardware stores. It can make a world of difference! Restricted air flow can cause your AC to overheat and shut off. Regular cleaning will extend the life of the air conditioner. 2. Make sure the tip of the FIN/Frost SENSOR is in the right place. On new units it's the wire coming out the bottom under the word "FINS" on older units it the longer wire coming out of the top right side. After the ice melts, watch your a/c unit as it's cooling. Where does frost FIRST start to form? That's where your sensor tip needs to be. Note for Mini-split users only: For a few mini-split air conditioners, the ice starts forming around the "top and back" of your wall unit. It's hard to notice that, but check if you have tried the other things and you are still getting ice up. It's difficult to move the fin sensor to the back, but it's important if yours is one of the minority units that do start to ice up in the back. 3. Check the calibration of the CoolBot sensors:

Gently slip the fins sensor out of the face of the air conditioner.  If the sensor is frozen in the face of the air conditioner thaw the ice first.  You can wait for it, or use a hair dryer but if you force it out it will break.  Wait about 2 minutes for the fins sensor to register the air temp then using the arrow keys on the CoolBot click back and forth between the room and fins modes and compare the temperatures. If the sensors read more than 3 degrees different then one is broken.   Determine which one is bad and throw it away!  One may be reading obviously wrong or you can compare the temperatures to another thermometer. Workaround mode:  The room and fins sensors on the CoolBot are interchangeable. We are going to determine which one is bad and only use the good one! If the sensors are calibrated and if you're still getting ice on the fins: Keep going up 1 point until the problem is solved. If you have to go up above "4" then skip to the next step, below.