Before you start to investigate this problem make sure that the power source to the refrigerator has been turned off. Make sure that you have a multitester, screwdriver and a pen and something to label the wires.
Most multitesters are hand-held with an LCD display. They have two wires referred to as leads. One wire is red and the other is black, with metal tips called probes.
The multitester will be your aid in diagnosing electrical issues and you will also use it to measure resistance. The way this is done is by measuring the ohms - resistance of the wire to flow of electricity. The range of ohms goes from zero to infinity. A reading of zero ohms shows that it is very easy for the electricity to flow. A reading of infinity means there is no path for the electricity to go through.
The thermostat is wired together with the defrost heater. When the thermostat opens the heater shuts off.
Remove all contents of the freezer including the shelves, icemaker parts, and the inside rear, back or bottom panel. Some older refrigerators require that you move plastic molding before you can gain access to the freezer floor. If your refrigerator unit is older and requires this step, try warming the molding with a wet cloth before removing. When the molding is hard and dry it tends to break easily.
There are two wires connected to the thermostat. Pull on the connections until they are no longer connected to the terminals. Do not pull on the wires themselves.
Now remove the thermostat from the unit. You may have to unscrew, clip or clamp it.
Set the multitester to R X 1 ohms. Place each lead on a thermostat wire. When the thermostat is cold you should get a reading of zero; when warm you should get a reading of infinity. If you get any results that are different you will need to replace the thermostat.
Since the thermostat is already removed, simply insert the new thermostat into place connecting the wires to the replacement thermostat wires, panel and restore the power.
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