The thermistor is an integral part of the GE thermostat system. It is a simple device made out of very specific metals and charged with a specific electrical current. The thermostat measures the resistance that the current is experiencing through the metals. Because the resistance is affected by the temperature, this tells the thermostat how cold the compartment is. It adjusts the temperature to an appropriate range.
The ohmmeter will measure the electrical current in ohms. If you elevate the thermistor temperature to above freezing and test its connections by attaching it to the ohmmeter, it should read around 16.6 K ohms, plus or minus 5 percent. GE refrigerators have four or five thermistors. If they do not read the correct amount of ohms, they are faulty and need to be replaced.
If you suspect you may have a thermistor problem but do not want to take out all your thermistors and test them, watch for certain signs your refrigerator is malfunctioning. If your refrigerator is not cycling, or if the compressor is constantly running no matter what temperature range you set, something may be wrong with the thermistor. It means defrost cycles may not work, and your refrigerator will become less efficient in general. Check and clean your compressor coils to make sure they are operating correctly before you start taking out your thermistors.
If the thermistor itself has a bad ohm reading, the only solution is to completely replace the thermistor. You can purchase new thermistors and attach them to your GE refrigerator to solve the problem. If the thermistors are functioning correctly, but the thermistor attachments on the control panel are faulty, you may have to replace the entire control panel to fix the fridge.