Heat Pump Frozen Outside

When this becomes an emergency

• The coil is buried under solid ice rather than a light rime that clears on its own.
• The top grille and fan blades are locked or the fan is chopping at slush.
• Indoor air has gone lukewarm and the backup heat is carrying the load.
• Melt from the roofline above has refrozen around the base into a solid pad.

What a pro does

Light frost between defrost cycles is ordinary and isn't a fault. A solid casing of ice is a system that has stopped clearing itself, and the reasons cluster into a short list. The defrost control may not be initiating, either because the board has failed or because the coil sensor has drifted out of range. Charge may be low enough that the coil runs colder than design. Airflow across the coil may be restricted by leaves packed into the fins from fall, which happens constantly with units squeezed between a house wall and a lot line where debris has nowhere to blow. The other big one around here is water from above. A unit sitting under an unguttered eave gets soaked every thaw, and that refreezes into a block no defrost cycle was designed to fight. A tech watches an actual defrost sequence, checks the reversing valve, and reads pressures. Chipping at the fins with anything hard wrecks the coil.

Frequently asked questions

Heat Pump Frozen Outside?

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