A thermal fuse is an electrical switch that is designed to shut off the flow of heat when temperatures rise to dangerous levels. Overheating or malfunctioning can cause the thermal fuse to trip. This safety measure is used in heat-generating appliances, such as clothes dryers, hair dryers and coffeemakers.
Clothes dryers that no longer blow hot air may have a blown thermal fuse. Thermal fuses do not have the ability to reset on their own and must be replaced once they are tripped or blown. Replacing a thermal fuse should be done quickly, as functioning thermal fuses help prevent fires.