If you have a refrigerator that cannot hold the correct temperature, the problem may be something as simple as a defective thermostat. Before you call for costly repairs on your compressor or condenser coils, test the thermostat to make sure it is sending the proper signals to the rest of the refrigerator. Turn the temperature dial down to a lower setting and listen for the sound of the compressor. If it does not attempt to start, replace the thermostat and test the refrigerator again.
Unplug the refrigerator's power cord from the electrical socket. You can also flip the kitchen's breaker switch at the home's circuit breaker box if the electrical socket is too hard to reach.
Consult your refrigerator's owner's manual to find the location of the thermostat. This is generally at the back of the freezer or under the floor panel for a freezer-on-top refrigerator. For a side-by-side refrigerator, the thermostat is usually in the rear of the freezer. You may have to remove the ice maker bin to access the thermostat.
Open the panel that covers the thermostat. Remove any screws or clips that hold this panel in place. Gently pull the ends of the wires off of each terminal of the old thermostat with needle-nose pliers. Remove any mounting hardware securing the thermostat and gently pull the thermostat away from the evaporator tube.
Insert the replacement thermostat and tighten the mounting hardware. Connect the electrical wiring to the terminals of the new thermostat.
Set the temperature dial inside the refrigerator to your desired setting. Plug the power cord back into the electrical socket or flip the breaker switch back to the "on" position. Listen for the sound of the compressor as the refrigerator cools down to the proper temperature. If it is still not running, call a professional as the repair is probably beyond the average homeowner's skill level.
Clear out any debris that may be blocking the condenser coils before running your refrigerator again. Blocked coils may burn out the new thermostat prematurely.