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HomeRepair HelpThermador Refrigerator RepairThermador Refrigerator not defrosting Repair
Thermador Refrigerator not defrosting
If your Thermador refrigerator is not defrosting, the most likely cause is simple ice buildup from a door left open or not sealing properly — that can frost the evaporator coil and stop normal defrost cycles, and small freezes often clear after a cycle while heavy ice may need the unit unplugged for a day or careful warming with a hair dryer. After ruling out a door issue, bad defrost electronics are the next suspects: a failed defrost control board or a defrost timer that won’t advance can prevent the heater from running. Less likely but still common are a warped or worn door gasket that lets moist air in, a defective defrost heater assembly that lacks continuity, or a faulty defrost thermostat that won’t close to allow heater power. Start by checking door seals and any visible ice, then test the defrost heater and thermostat with a multimeter before replacing the control board or timer. Enter your model number on RepairClinic.com to see the exact replacement defrost parts that fit your refrigerator and get step-by-step guidance for the repair.
01 - Door left open
If the freezer or refrigerator door was left open for an extended period of time (more than 4 hours), frost or ice may have accumulated on the food, evaporator coil and evaporator fan motor, or around the door opening. Frost should go away after the door is closed and the refrigerator goes through a defrost cycle. More significant ice buildup may require the refrigerator to be unplugged for a day to allow the ice to melt, or a hair dryer may be able to be used to assist in melting the ice.
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02 - Thermador Refrigerator Defrost Control Board
The defrost control board determines how often to run the defrost cycle. If the board fails, the refrigerator 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.
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03 - Thermador Refrigerator Defrost Timer
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, this indicates that the defrost timer is not advancing. If ...
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04 - Thermador Refrigerator Door Gasket
A twisted or worn gasket can keep the door from closing properly. Inspect the door gasket for kinks or twists. You can use a hair dryer to try smoothing out the kinks. If the door gasket is damaged it will need to be replaced.
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05 - Thermador Refrigerator Defrost Heater Assembly
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.
Common
06 - Thermador Refrigerator Defrost Thermostat
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...
Common
Frequently Asked Questions
My Thermador refrigerator not defrosting — what are the most likely causes?
How do I test the defrost heater and defrost thermostat?
How can I tell if the defrost control board or defrost timer is defective?
There is heavy ice buildup because a door was left open — how do I clear it safely?
How do I enter my model number on RepairClinic.com to find the correct replacement part?
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