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Testing Defrost Heater on Samsung Refrigerator RF28HFEDBSR/AA09


Premium Member
Sep 5, 2022
Model Number
6-10 years
Hello! I'm getting frost buildup around the condenser fan in my Samsung refrigerator RF28HFEDBSR/AA09. After a block of ice forms, the fan stops and then the cooling stops.

I'm wondering if the problem is the defrost heater/thermostat or the board that has the defrost control.

I installed a secondary heater. The defrost thermister worked fine through multimeter testing when I installed the secondary heater. Additionally, the heaters came on when I manually placed the refrigerator in "rd" mode (magnets on top to simulate closed door).

I presume that the defrost heater would not come on in "rd" mode if the integrated defrost thermostat was faulty, even if the defrost heater itself was fine?

As a test, I manually placed the frig in "rd" mode twice a day. After a week, there was very little ice buildup, unlike the small block of ice I was expecting if the heater did not work in "rd" mode.

Since the defrost heater comes on in "rd" mode, does this imply that the defrost control board is faulty and is not routinely activating the defrost heater? From what I've read, that should happen two to three times a day?

Thank you and best regards.


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