Answer Bernt, You would want to test the defrost thermostat, defrost heater for continuity. If they test ok then test the sensor for resistance of 5K ohms at room temp. If this checks ok then the control board would be the issue. If the unit is having a defrost issue the evaporator coils would be completely iced up. Read More... Answered by AppliancePartsPros.com | Monday, February 25, 2019