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HomeRepair HelpThermador Refrigerator RepairThermador Refrigerator has frost or moisture buildup around the door Repair
Thermador Refrigerator has frost or moisture buildup around the door
Frost or moisture building up around the mullion flap or between your Thermador refrigerator doors is usually a seal or heater problem that lets warm, humid air into the cavity. The top suspect is a failed mullion heater; use a multimeter to check for electrical continuity and replace the heater if it reads open. If the heater checks out, inspect the door support and door guide next — bent, worn or misaligned parts prevent the mullion flap from forming a tight seal. Also check the door gasket for twists, tears or hardening, since a bad gasket can let warm air in and leave the freezer cold but the refrigerator warm or cause the freezer not to freeze properly. Sometimes the cause is simpler, like a door left open for several hours, which produces frost that will clear after a defrost cycle. If you need replacement parts like a mullion heater, door support, guide or gasket, enter your model number on RepairClinic.com to find the exact part that fits your fridge.
01 - Thermador Refrigerator Mullion Heater
A defective mullion heater flap may not be able to heat up periodically to melt any frost or moisture that forms on the flap due to increases in room humidity. You can use a multimeter to test the mullion heater for electrical continuity to determine if the component is working. If the mullion heater has no electrical continuity you should replace it with a new one.
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Common
02 - Thermador Refrigerator Door Support
If the mullion heater flap has frost or moisture buildup, it's possible the door suport is damaged or misaligned and not allowing the flap to form a tight seal between the refrigerator doors. Inspect the door support for wear or damage and replace if necessary.
Common
03 - Thermador Refrigerator Door Guide
If the mullion heater flap has frost or moisture buildup, it's possible the door guide is damaged or misaligned and not allowing the flap to form a tight seal between the refrigerator doors. Inspect the door guide for wear or damage and replace if necessary.
Common
04 - Thermador Refrigerator Door Gasket
A door gasket should form an airtight seal around the appliance's frame to keep the cold air in and the warm air out. If the door gasket is twisted or torn, gaps can form that will allow warm air in, resulting in the freezer not freezing properly. Inspect the door gasket for any damage and replace with a new one if necessary.
Common
05 - Refrigerator or freezer door left open
If the freezer or refrigerator door was left open for an extended period of time (more than 4 hours), frost may have accumulated on the food and around the door opening. The frost should go away after the door is closed and the refrigerator goes through a defrost cycle.
Common
Frequently Asked Questions
Fridge not cooling but freezer works — could frost around the mullion be the cause?
My refrigerator has frost or moisture buildup around the door — is it not defrosting?
How can I test the mullion heater?
Fridge door not closing properly — how do I check the door gasket, support, and guide?
How do I enter my model number or part number at RepairClinic.com to buy the right replacement part?
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