Heat Pump Frozen Outside

When this becomes an emergency

• The outdoor unit is wearing a solid jacket of ice rather than a light dusting of frost.
• Ice has filled in under the coil and locked the fan blade in place.
• The indoor heads have gone lukewarm and the backup heat is carrying the house.
• Blowing snow has drifted up over the top of the cabinet and stayed there.

What a pro does

Frost on an outdoor coil is normal operation and the defrost cycle is supposed to clear it every so often. Solid ice is a different animal. A tech confirms whether defrost is actually initiating and terminating on schedule, checks the coil sensor and the reversing valve, and reads the charge, since a unit running low on refrigerant will ice up early and often no matter how healthy the defrost board is. Placement's worth a look too. Up here the failure is frequently mechanical rather than electronic: drifted snow packed against the coil, a unit sitting too low on its pad, or meltwater off a roofline refreezing under the fan and building a block of ice from the bottom up. Prying at that ice with anything metal bends fins and cuts refrigerant lines, so don't. Shutting the unit down and letting it drain is the safer wait.

Frequently asked questions

Heat Pump Frozen Outside?

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