Where is the defrost heater thermostat?

Hi @raybo99 ,

Here’s some information that may help.

According to the parts supplier below the Cover sheet part # is W10747668.

On p.3 Cabinet parts of the above document it shows that the tech sheet is part #W10653921.

This sheet details the diagnostic test modes and also has the wiring diagram.

Looking at the parts diagram for your model, there are only 2 thermistors shown.

They are shown as part #3 Liner parts diagram and part #9 unit parts diagram.

I think that part #9 is the defrost thermistor as it looks like it is meant to clip onto the evaporator unit or close by.

The wiring diagram shows that the evaporator thermistor (defrost thermistor?) can be tested from the control board connector CN2 pins 1 & 2

As best that I could find out regarding the specifications for the thermistor (part #WPW10383615) is that at room temp of 77°F the resistance should be 2.7KΩ (2700Ω) and at 36°F (in ice water) it is 7.964KΩ (7964Ω). being an NTC (negative temperature coefficient) type thermistor the warmer the temperature the less the resistance.

Regarding the defrost thermistor part number see Note.4 on p.2 of the sheet

Although if the actual model number (not a Whirlpool part number) of the thermistor is visible on it then try verifying the specifications by searching online using the model number only to see if they’re available. It should never measure open circuit.

Looking at the wiring diagram in the tech sheet it also shows that there is an inline thermal fuse connected on the brown wire between the harness connector and the heater element although I cannot find it listed in the parts diagrams. It may also be worth checking if you can find it and test if it is OK also given that you said that the defrost heater element is OK.

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