Heat pump iced up or stuck in defrost?

What usually causes this

These are the common possibilities, not a diagnosis. A page cannot tell which one it is — that takes a technician testing the system.

Defrost control or sensor failure

The board or sensor that starts defrost fails, so frost builds into ice.

Outdoor fan problem

A fan that doesn't stop and restart correctly during defrost can prevent ice from clearing.

Low refrigerant charge

Low charge makes the outdoor coil run colder and ice faster.

Water dripping onto the unit

A gutter or roof edge dripping onto the unit can freeze on top of it.

Blocked coil or poor drainage

Debris, snow or a unit sitting too low can trap meltwater, which refreezes.

What you can safely check yourself

• Watch for about an hour. A normal defrost clears the frost within minutes.
• Clear snow, leaves and debris from around and under the unit.
• Check whether a gutter or roof edge drips onto the unit.

What we check when we get there

1. 1The technician tests the defrost board, sensors, reversing valve and outdoor fan operation, and checks the refrigerant charge.

What it is likely to cost

A defrost board or sensor is a mid-range repair. A refrigerant leak costs more. You'll know the price before work begins.

Diagnostic

$89

Defrost control board

From $349

Outdoor fan motor

From $449

Refrigerant leak / recharge

From $499

Prices are starting points for standard work in the Savannah area. Final price depends on the system and site, and is confirmed before work begins. Permits and code-required upgrades may be additional.

Questions people ask about this

Is steam from my heat pump normal?

Yes. During defrost the outdoor unit heats its coil to melt frost, and the melting frost gives off steam. It usually lasts a few minutes.

Why is cool air coming from the vents in winter?

Almost certainly a defrost cycle. The system briefly reverses to clear frost. Repeated or very long defrost cycles aren't normal.

Where to go next