Heat Pump Frozen Outside

A heat pump encased in ice keeps losing output every hour it runs that way, so call before the backup heat is carrying the whole house.

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When this becomes an emergency

The outdoor coil is buried under solid ice rather than a thin white frost.
Ice has built up from the pad to the fan guard and is not clearing.
Indoor heads are pushing air that feels barely warmer than the room.
The outdoor fan is striking something and making a chopping sound.

What a pro does

Frost that comes and goes with the defrost cycle is ordinary, and the question is whether this system is clearing itself or falling behind on what it should be shedding. A technician watches for a defrost cycle to initiate, checks the board and the coil sensor that trigger it, and reads the refrigerant charge, since a low charge drives coil temperature down and makes ice form faster than defrost can shed it. Placement gets attention too. Units retrofitted onto older homes frequently ended up under a roof edge or tight against a foundation where snowmelt drips and drifted snow pile up around the base. Prying ice off with a tool bends fins and adds a repair that wasn't there before and turns a service call into a bigger one.

Frequently asked questions

How much ice is normal on a cold morning?

A light coat of frost across the coil is normal between defrost cycles. A shell thick enough to hide the fins or lock the fan is not.

What does defrost actually do?

The system briefly reverses itself and sends warm refrigerant out to the coil to melt what's collected, which is why the outdoor unit sometimes steams and the indoor air cools for a few minutes.

Does drifting snow around the unit matter?

It does. A base packed with snow or a coil blocked on one side chokes airflow, and the ice that forms after that has nowhere to drain when defrost runs.

Is it better to shut the system off until someone comes?

Switching to the backup heat source and letting the outdoor unit thaw on its own is reasonable, and it spares the compressor from working against a blocked coil.

Heat Pump Frozen Outside?

Get connected with a local pro now.

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