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HomeRepair HelpThermador Refrigerator RepairThermador Refrigerator defrost drain clogged Repair

Thermador Refrigerator defrost drain clogged

A clogged defrost drain in your Thermador refrigerator usually shows as water pooling in the bottom of the compartment or repeated ice build up in the evaporator area. The most likely causes, in order, are a failing evaporator fan motor that lets cold air migrate and freeze the drain, a frozen or otherwise clogged defrost drain and tube, a missing or damaged drain strap that should conduct heat into the drain, a faulty drain heater, and, less commonly, a defective main control board that interrupts the defrost cycle. Start by verifying the evaporator fan spins freely and runs, clear ice from the drain with warm water and a turkey baster, and inspect the drain strap and heater for proper position and continuity. You can test the fan motor windings with a multimeter before replacing the motor. Enter your model number on RepairClinic.com to find the exact replacement evaporator fan motor, drain strap, drain heater, or control board for your refrigerator and the repair parts that fit your unit.

01 - Thermador Refrigerator Fan Motor

If the refrigerator's defrost drain is clogged, it's possible the evaporator fan motor is not working. If the evaporator fan is not running, cold air from the evaporator can migrate to the defrost drain causing ice buildup in the drain. To determine if the evaporator fan motor is defective, try turning the fan blade by hand. If the fan blade does not turn freely, replace the fan motor. Additionally, if the motor is unusually noisy, replace it. Finally, if the motor does not run at all, use a multimeter to test the motor windings for continuity. If the windings do not have continuity, replace the evaporator fan motor.
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02 - Clogged or Freezing Defrost Drain

The defrost drain might be clogged or frozen. If the defrost drain is frozen, the water will overflow the drain trough and drip down to the bottom of the compartment. You can use a turkey baster and warm water to help clear out a frozen defrost drain and tube. You should also make sure the drain tube trap is clear by the drain pan.
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03 - Thermador Refrigerator Drain Strap

Some defrost drains are outfitted with a drain strap. The drain strap is a small piece of copper or aluminum that attaches to the defrost heater and extends partway into the defrost drain. When the defrost heater turns on, heat is conducted through the drain strap to melt away any ice that may have accumulated further down in the defrost drain. If the drain strap is not in place, the defrost drain may be more likely to freeze over.
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04 - Thermador Refrigerator Evaporator Fan Motor

If the refrigerator's defrost drain is clogged, it's possible the evaporator fan motor is not working. If the evaporator fan is not running, cold air from the evaporator can migrate to the defrost drain causing ice buildup in the drain. To determine if the evaporator fan motor is defective, try turning the fan blade by hand. If the fan blade does not turn freely, replace the fan motor. Additionally, if the motor is unusually noisy, replace it. Finally, if the motor does not run at all, use a multimeter to test the motor windings for continuity. If the windings do not have continuity, replace the evaporator fan motor.
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05 - Thermador Refrigerator Drain Heater

Some refrigerators are equipped with drain heaters. Drain heaters prevent the water in the drain pan from re-freezing and clogging the defrost drain. If your drain heater is defective or is not in the proper position, the defrost drain might freeze over.
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06 - Thermador Refrigerator Main Control Board

The main control board regulates the power supply to all of the refrigerator components, including the defrost system. If the main control board is defective, it may stop sending voltage to the defrost system which can lead to the defrost drain becoming clogged with ice. 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 control board.
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Less Common

Frequently Asked Questions

Why is my defrost drain clogged?
Fridge not cooling but freezer works — can a clogged defrost drain or bad evaporator fan cause this?
My refrigerator is leaking water on the floor, could a frozen defrost drain be the cause?
How can I tell if the evaporator fan motor or main control board is bad?
How do I enter my model number or part number at RepairClinic.com to find the right replacement part?

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