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GE Refrigerator Appliantology: Dampers and Thermistors

Samurai Appliance Repair Man


This is the next in a series of posts I’m doing about the technology used in GE refrigerators. Understanding the basics of how these refrigerators work will give you a lot of troubleshooting insight when you’re trying to track down a problem.

For the previous post in this series on controlling and operating the fan motors in GE refrigerators, see this page.

This post gives useful tips and Fun Facts to Know and Tell for diagnosing the Damper Door and Thermistors.

Damper Door

The Damper Assembly has two motors: one to open the Damper Door and another to close it.

The Damper Door should always be either fully open or fully closed; if you ever see it in a halfway state, there’s a problem. Check it in diagnostic/self-test mode where you can run a test to open and close the damper door.


Thermistors are basically variable resistors whose resistance changes with temperature. They come in two flavors: Positive Temperature Coefficient (PTC) and Negative Temperature (NTC). In the PTC thermistors, the resistance increases with increasing temperature whereas in NTC thermistors, the resistance decreases as the temperature increases. All thermistors used in GE refrigerators are NTC.

Most of the side-by-side units will have four thermistors:

- attached to the evaporator coil

- freezer space

- beer section space

- damper

You can see a diagram showing thermistor locations in side-by-side units here ==> LINK

Units with the Custom Cool feature will have a fifth thermistor for the Custom Cool compartment. Lower end units will just have three thermistors.

In all units, the thermistor attached to the evaporator coil is the most troublesome.

There was a rash of problems with one of GE’s old thermistor suppliers a while back where they weren’t sealed properly so moisture got into ‘em and knocked ‘em out of calibration. More about that here ==> LINK

The refrigerator control has a self test for the thermistors, but it only tests if they’re open or closed. In real life, the thermistors rarely fail that way– usually they simply go out of calibration resulting in poor temperature control.

To learn more about your refrigerator, or to order parts,

click here.

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Just ran into my second GE SXS unit that had an open thermistor during the self diagnostic test.  All passed except #5.

Replaced the Freezer thermistor first and then the main board.  Still showed open on the self test.

Unit still reads an “actual” temp though.  If it was open, should it show a temperature or have an error code?


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I would say yes but that may depend on operating range and if that sensor is communicating 

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Turns out the new board was “used”.  This particular unit had a Smart HQ dongle behind the kick plate.  Model number pulled as an entirely different unit.  Returning board, ordering new one, and double check everything.

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