The newer GE and Hotpoint refrigerators– the ones with the muthaboard on the back– use thermistors to sense temperature in the freezer, beer compartment, and evaporator. The motherboard on the back of the refrigerator sends an electrical pulse to the sensor to measure its change in resistance and thus sense the change in temperature of the refrigerated space. The older thermistors had a defective seal which allowed water to seep in. This messes with the resistance and sends weird signals to the muthaboard resulting in erratic temperature control. The picture below shows the difference between the new and old-style thermistors (click for larger view):
If you’re having temperature control problems in your GE fridge, check to see if you have the old-style thermistors. If you do, you should replace all of them. Most models have four: two in the beer compartment, one in the freezer, and one mounted directly on the evaporator, shown in the diagrams below (click ’em for a larger view).
Here’s the new-style thermistor you need: