Heat pump encased in ice or defrosting constantly
Trane's line: if the heat pump seems to be constantly switching into defrost, or the cycles get longer and frost and ice start to cover the unit, call for service. A coil buried in ice cannot move heat and the compressor is working against it.
What is probably happening
- The defrost control, its sensor, or the reversing valve has failed, so the unit never melts what it builds.
- Low refrigerant from a leak makes the coil run colder than it should and ice faster.
- A gutter dripping onto the unit, or snow packed around it, can also encase it. Check that first.
- The outdoor fan may have stopped, so no air moves across the coil.
Do this in the next five minutes
- Switch to EMERGENCY or AUX heat to keep the house warm and stop the compressor grinding on ice.
- Clear snow from around and on top of the unit. Look for a downspout or roof drip line feeding it.
- Do not chip at the ice. Let it melt on its own.
- Check the filter indoors.
- Book a visit and say: outdoor unit iced over, running on emergency heat.
Do not
- Do not run it in normal heat mode while it is solid ice.
- Do not leave it on emergency heat for weeks. Electric strip heat costs far more to run than the heat pump, so get it fixed.
Who to call
A licensed HVAC technician with EPA Section 608 certification
Defrost boards, reversing valves and refrigerant charge are heat pump specific work. Ask whether the technician regularly services heat pumps.
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What it should cost
$200 to $2,000
Heat pump repair, national range. A refrigerant leak repair is $250 to $1,500
Source: Angi, HVAC repair cost, updated August 2026. View source
National published range, not a quote for your job. The full cost table for this trade is on the hvac page.
Ask this contractor, on the phone, before anyone comes out
Tap each one as you ask it.
- Was it the defrost board, the sensor, the reversing valve, the fan, or refrigerant? What did you measure?
- If it is low on refrigerant, where is the leak, and is fixing it in the price?
- Is anything dripping onto the unit that will ice it again?
- What is your EPA Section 608 certification type?
End the call if
- A refrigerant top-off with no leak found.
- A replacement quote where the only finding is a failed defrost sensor or board.