Freezers guide for troubleshooting the thermostat-temp control...
The thermostat or more commonly referred to as the "temp control" is critical for proper operation of your freezer. The thermostat basically tells the compressor when to run and when to "shut off" when it reaches it's designed temperature parameter.
One easy and non technical way to verify whether a thermostat is good or bad is your ear....YES, your ear. A good thermostat will "click" off and on when turned either way to the max (0 or 9). If you do not hear a click, it is likely the thermostat is shot.
Typically, when the thermostat does go bad - one of two things happens. Either the unit will not run-period OR it won't shut off. When the latter happens, the freezer typically runs and runs and runs until it takes out some other component of the freezer, most commonly, the compressor.
Another option to verify a proper functioning thermostat is to temporarily eliminate it. Most freezers by design allow fairly easy access to the thermostat. If you feel comfortable with a screw driver, simply remove the screws to expose the thermostat (WARNING! first ensure the power to unit is off and the freezer is unplugged). Next, unplug the two wires that are connected to the thermostat. A simple jumper wire plugged into the two connectors will bypass the thermostat. This is ONLY for test purposes and should NEVER be done to keep your freezer operational. As stated earlier, if you bypass the thermostat with a jumper wire and the freezer runs, it will NOT shut off while the jumper wire is in place and will certainly cause further / more expensive damage.