12/08/2025
Attention heat pump owners: Due to the weather, we are fielding calls for heavily frosted or iced heat pump outdoor units today. Is your outdoor unit starting to look like a snowball or an ice sculpture?
Your heat pump normally develops frost as it runs in the heating mode below 50F outdoor temperature, and it has an automatic defrost feature that thaws it periodically. When the outdoor temperature is at or slightly above freezing, AND there is borderline frozen precipitation (snow or sleet), the “perfect storm” conditions are present to freeze up any heat pump depending on factors such as how long run-cycles are, which way the wind is blowing, etc. These conditions can develop frost and ice faster than the defrost system can remove it. Freezing rain and sleet can freeze the fan blade to the shroud in some cases. In a nutshell, your heat pump will not heat if it is frozen, and running when frozen can damage your heat pump.
If your indoor temperature starts dropping today, take a look at your outdoor unit to see if it is frozen. If it is, go to your thermostat and switch the system setting to ‘emergency heat’. This will turn off the outdoor unit and rely solely on backup resistance heat.
Once the borderline frozen/wet weather passes and your outdoor unit thaws, change the system setting back to the normal ‘heat’ setting.
This scenario isn’t necessarily a reason for a service call, but if your outdoor unit freezes during normal operation, then you may have an issue requiring service.
Stay warm!