Let me start by admitting I don't have specific information on your model. Unplugging the thermistor will not generally work unless the electronic control has a failure mode that over rides the open circuit. The thermistor is used to tell the control the temperature in the refrig side. This information is used by the control to open an air door etc to allow cool air or refrigerant flow into the refrig side. You would need an ohm meter to test the thermistor. The resistance changes as the temperature changes.