FieldBench
Carrier codes

Carrier

Defrost

Protect

Defrost fault

Stuck in defrost or never defrosts.

Walk Defrost in Diagnose

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First check

1 Is it actually in defrost?

On Carrier 50FC confirm the board thinks it is in defrost: OD fan off, RV shifted, indoor calling heat/aux. A failed OD fan in heat ices the coil and looks like a defrost board. OD coil sensor / defrost control on this packaged HP.

Expect: Defrost only with a cold outdoor coil, not on every call.

The rest of the walkthrough is Diagnose.

On the plates

  • OD coil sensor / defrost control on this packaged HP.
  • Aux heat on during defrost is normal. Aux heat only, all day, is not.

Plates that use Defrost