WHIRLPOOL FRIDGE WRF535SWHZ NOT COOLING Repair

Defrost Heater

Excessive ice buildup on the evaporator coils indicates a failure in the automatic defrost system. The defrost heater is responsible for melting this ice during the defrost cycle. If it has failed, ice will accumulate and block airflow to the fresh food compartment, causing it to warm while the freezer remains cold.

Defrost Thermostat

The defrost thermostat (or bimetal thermostat) acts as a safety switch, allowing power to the defrost heater only when the evaporator coils are cold enough. If this component fails in an open circuit, the defrost heater will not receive power, leading to ice accumulation on the coils and restricted cooling in the refrigerator section.

Defrost Timer / Control Board

The defrost timer, often integrated into the main control board, is responsible for initiating and terminating the defrost cycle at regular intervals. If this component malfunctions, it may fail to trigger the defrost heater, resulting in continuous ice buildup on the evaporator coils and subsequent loss of cooling in the fresh food compartment.