Keep a refrigerator from freezing by replacing the thermostat or the temperature sensing tube, advises the San Francisco Chronicle. A thermostat stuck in a closed position or a temperature sensing tube that has lost its charge results in a refrigerator that freezes.
Unplug both the refrigerator from the wall and the wiring harness from the terminal board, the San Francisco Chronicle explains. A pictorial wiring diagram of the refrigerator is required so that you can find the specific parts to test and replace. In order to find the thermostatic control and terminal board, consult the wiring diagram, and use a DMM. or digital multimeter, to test the thermostat. The meter should display an O.L. while the thermostat is off or 0.000 when the thermostat is on. If the meter displays anything else, the thermostat is faulty. If the thermostat is working, the temperature sensing tube or bulb is probably faulty.
Once the problem has been determined, the next step is to find replacement parts, says the San Francisco Chronicle. Remove the thermostatic control, and take it to an appliance parts supplier. After obtaining the correct part, place it in the right location in the refrigerator and replug the wiring harness.