Goodman
Stuck defrost
ProtectDefrost sensor / board
Outdoor iced in heat, or runs cool-mode steam in heat all day.
Walk Stuck defrost in Diagnose
Sign in for the next measurement
First check
1 Is it actually in defrost?
On Goodman GSZ14 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. Outdoor coil sensor ohms vs the defrost-board chart.
Expect: Defrost only with a cold outdoor coil, not on every call.
The rest of the walkthrough is Diagnose.
On the plates
- Outdoor coil sensor ohms vs the defrost-board chart.
- Board in test pins — do not leave it in forced defrost.