How to Reset a Thermal Fuse

If you're wondering how to reset a thermal fuse because your clothes dryer overheated, you're on the right track, but a thermal fuse — as opposed to a thermal switch — is not resettable, and if one blows and the appliance stops heating or won't work at all, you have to replace it like you do an old-style electrical fuse. It isn't just clothes dryers that have thermal fuses; pretty much any appliance that heats up has one, including your washer, microwave oven, standard electrical oven, dishwasher and room heater. There's even a thermal cutoff fuse on your refrigerator because the compressor can overheat, but the blower on your central heating fan is more likely to have a resettable thermal switch.

The thermal fuse is a safety device that prevents fires by shutting off the power either to the heating element of the appliance or the entire appliance, so if your electric dryer feels unusually warm and it won't turn on, the thermal fuse has probably blown, and the dryer won't work even when the temperature drops. Replacing a thermal fuse is easy, and the replacement is inexpensive, but accessing the fuse may not be easy, and depending on where the manufacturer put it, it may require a fair amount of disassembly. In many cases, however, you can get to it by just removing the front or back panel of the appliance.

When an appliance like an electric dryer overheats and the thermal fuse blows, your first clue is usually that the appliance won't turn on. In addition to a thermal fuse, most electric dryers also have a high-limit thermostat to prevent overheating, but it typically just shuts off the heating element, and the dryer stops heating. The thermal fuse in a dryer is located near the exhaust blower, and a common cause of a blown fuse is lint buildup in the dryer vent blocking airflow, so a good way to troubleshoot the problem is to clean the exhaust vent.

Dryers can lose power for other reasons, including a blown circuit breaker or GFCI outlet, a faulty door switch or some other problem in the control panel. If the thermal switch is accessible enough, it's easy to determine whether or not it's the problem by performing a continuity test with a multimeter, so it's one of the first things to check. Some dryer designs, however, call for extensive disassembly — including removal of the dryer drum — to get to the thermal fuse, which makes it more practical to eliminate other possibilities before going to the trouble of checking the thermal fuse.