Hi @albert29972,
- If the diagnostic defrost heater test overrides checking if the bi metal defrost thermostat is reset i.e. contacts are closed
then just verifying that with the power disconnected from the refrigerator and the 7 pin evaporator harness cable unplugged from the J1 connector on the board that you're measuring the defrost heater resistance when an Ohmmeter is connected across pins 1 & 3 of the J1 harness cable plug?
If not then there's an open wire somewhere on the path from pin 1 of the cable plug to and through the defrost heater and then back to pin 3 You may have to do point to point testing along the wiring path to find out where.
- If the diagnostic defrost heater test doesn't override checking the defrost thermostat,
did you allow enough time for the refrigerator to cool down to the set temps before checking if the defrost heater worked?
The bi metal defrost thermostat contacts need to be closed as this tells the control board that it is OK to turn on the defrost heater when a defrost cycle is started. i.e. the defrost heater voltage is also applied via the closed defrost thermostat contacts to pin 5 in the cable i.e. from control board pin 1 though fuse and the heater, through the thermostat and onto pin 5
The part number for the defrost thermostat in your model is WPW10165425 and the best that I can find out online is that it is a L42-30F type (type number is usually shown on side of thermostat if you wish to verify). This means that the thermostat contacts will open when the temperature near the evaporator unit is >42°F and close again when the temp is <12°F. The thermostat is used to safeguard the evaporator unit from being damaged due to overheating during a defrost cycle as it is made of thin aluminium and designed to work in below freezing temperatures.
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