Heat pump · triage
Ice on the heat pump’s outdoor unit in winter
The short answer
A light coat of frost that clears every so often (sometimes with steam and a whoosh) is the normal defrost cycle. A unit encased in ice, or ice that never clears, needs attention this week.
No hot water or chippingDon’t chip ice off the coil or pour boiling water on it. Switch to emergency heat if your thermostat has it while you wait.
Know your shutoffs
Every outcome on this card
WatchNormal defrost
Nothing to do.
- Keep snow cleared from around and on top of the unit
- Keep the area under it clear so meltwater can drain
- Log it if it seems to defrost very often
Heat pumps pull heat from cold air; frost forms and the unit periodically reverses briefly to melt it.
This weekRoof water is freezing on the unit
Redirect the water this week.
- Switch to emergency heat if available
- Redirect the gutter or downspout away from the unit
- Let the ice melt naturally before running heat-pump mode
This weekDefrost isn’t working
Call a technician this week.
- Switch to emergency or auxiliary heat if available It costs more to run but protects the unit.
- Clear snow around the unit
- Call an HVAC technician A defrost sensor, control board, reversing valve or low refrigerant can stop defrost.
Related
Written from
Original casaq guidance, updated 2026-10-05. General guidance, not a diagnosis; licensed-pro review pending. Severity levels: Emergency now / Today / This week / This month / Watch. Send a correction.
Step 1