A defrost thermostat works in a refrigerator by regulating the temperature during a freezer’s defrost cycle. A homeowner usually sets preferred temperature that, upon attaining, the defrost thermostat shuts off current from travelling to the defroster elements.
Just as the thermostat in a furnace disconnects current to the house, a defrost thermostat regulates the flow of current in a refrigerator. In this regard, the heating elements of a refrigerator may fail to turn on when the defrost thermostat is faulty. On the other extreme, heat damage and fire may arise as a result of the thermostat’s inability to turn off the elements.
To diagnose a fault in the defrost thermostat, switch the unit off and detach the power cord from the wall socket. When locating the thermostat, note that different refrigerator models have thermostats in different locations. While it is usually under the compartment floor of a bottom-mounted freezers, the device may be located at an edge of the floor plate of a top-mounting appliance.
After removing the electric wires plugged on the thermostat terminal, use a multimeter to plug the red and black test leads onto their correspondingly colored jacks of the thermostat. The readout 0.000 should appear on the multimeter display when the thermostat is in a closed point. Otherwise, the thermostat is faulty and needs replacing.