It's cold outside and your heat pump has a bunch of ice on it. Some ice in winter is completely normal. Full-block ice is not.
You probably came here because…
- Ice or frost on the outdoor coil during winter operation
- Ice is more than a light coating – it's covering the fins
- You may notice reduced heat output when this happens
- The unit may sound different than usual
What’s actually happening
Heat pumps automatically defrost themselves. The system detects ice buildup, reverses direction briefly (running as an AC), melts the ice, then goes back to heating. You'll usually see steam rising off the unit during defrost.
Occasional light ice that clears within an hour = normal, working correctly.
Ice that keeps building up, ice covering the entire coil, or the unit running with a permanent slab of ice on it = defrost cycle isn't working. Usually a bad defrost board, stuck reversing valve, or bad outdoor sensor.
What we do about it
Watch for a defrost cycle
If you see ice building up, watch the unit for the next 30-60 minutes. You should hear a click, the outdoor fan should stop, and steam should rise off the coil as ice melts. If none of that happens over an hour, defrost isn't kicking in.
Kill the ice manually
If defrost isn't working and ice is building fast, switch the thermostat to Emergency Heat for a few hours. That runs the electric backup and gives the outdoor unit a chance to thaw naturally.
Don't chip at the ice
Never use a hammer, screwdriver, or chisel to break ice off a heat pump. The aluminum fins bend and puncture easily. Hot water works if you must – but really, just call us.
When to just call
If ice is building faster than the system can melt it, if you see a solid block of ice on the coil, or if the unit is making unusual grinding sounds, shut it off and call (423) 637-1846. Running a fully iced heat pump can bend the fan blade against ice and destroy the fan motor.
Ready to fix it?
Call the family that’s been doing this in the Sequatchie Valley since 1996.