The defrost thermostat monitors the temperature of the evaporator coils. When the coils drop below a set temperature, the thermostat contacts close to allow power to flow to the defrost heater during the defrost cycle. In the defrost cycle, the defrost heater melts away any frost that may have accumulated on the evaporator coils. If the defrost thermostat is defective, the thermostat contacts will not close. As a result, the thermostat won’t provide power to the defrost heater. To determine if the defrost thermostat is defective, use a multimeter to test it for continuity. If the defrost thermostat does not have continuity... when it reaches the low temperature of its operating range, replace it.
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The defrost timer turns on the defrost heater several times throughout the day to melt any frost that may have accumulated on the evaporator coils. If the defrost timer is defective, it may not advance into the defrost cycle, or it may not send power to the defrost heater during the defrost cycle. To determine if the defrost timer is defective, slowly advance the dial into the defrost cycle. The compressor should turn off and the heater should turn on. If the timer does not send power to the defrost components or advance out of the defrost cycle within 30 minutes, the defrost timer is likely defective and should be replace...d.
The defrost control board determines how often to run the defrost cycle. If the board fails, the freezer will not go into the defrost cycle. Before replacing the defrost control board, first test the defrost heater and defrost thermostat. If the defrost heater and defrost thermostat are working properly, the defrost control board is likely defective.
04 - Frigidaire Freezer User Control and Display Board
On some models the user control and display board may also control the defrost system. Control boards are frequently misdiagnosed—before replacing the user control and display board, first test all of the defrost system components. If none of the defrost system components are defective, consider replacing the user control and display board.
In a self-defrosting freezer, the defrost heater assembly turns on several times throughout the day to melt away any frost that may have accumulated on the evaporator coils. If the defrost heater assembly is defective, the defrost system will not work, and frost will continue to accumulate on the evaporator coils. To determine if the defrost heater is defective, use a multimeter to test it for continuity. If the defrost heater does not have continuity, replace it.
The control board has relays that send power to the freezer components. If the control board is defective, it may stop sending voltage to the defrost system. Control boards are frequently misdiagnosed—before replacing the control, first test all of the defrost system components. If none of the defrost system components are defective, consider replacing the control board.
The main control board regulates the power supplied to all of the freezer components, including the defrost system. If the main control board is defective, it may stop sending voltage to the defrost system. Control boards are frequently misdiagnosed—before replacing the main control, first test all of the defrost system components. If none of the defrost system components are defective, consider replacing the main control board.