Blown Thermal Fuse
A dryer will blow a thermal fuse if it’s close to overheating. Each time the thermal fuse blows it can interfere with a thermostat’s function and cause it to go bad, too. Generally, a dryer’s cycling thermostats will constantly cycle as a dryer’s temperature rises to the level that overheating may occur. The continued cycling that accompanies possible overheating wears out a thermostat faster than it otherwise might. Often when you have to replace a blown thermal fuse, you also have to replace a dryer’s cycling thermostats, according to the website Dave Repair.com.
Missing Screws
Two screws should secure a thermostat to a dryer. If one or both of a thermostat’s screws is missing, a thermostat’s wires can easily come loose and the thermostat won’t function properly. Ensure that each thermostat is firmly attached to the dryer, and that no screws are missing.
Faulty Wiring
If you have to replace a thermostat, make sure not to damage the wiring connections. Once the connections become bad, each replacement thermostat you install is liable to go bad. A thermostat is connected with metal or plastic slip connectors, which are attached to wires. Never pull the wires to disconnect a bad thermostat; slide off the connectors instead. Use needle nose pliers to ensure that you grasp the connectors when changing out a dryer’s thermostats, recommends the Part Select website.
Considerations
Each cycling thermostat is programmed for a different heat setting: low, medium and high. You can normally determine whether a thermostat is bad by testing the exhaust air temperature. A low heat setting should have an air temperature of 115 to 125 degrees F, medium heat of 130 to 140 F and high 145 to 155 F. If your dryer isn’t heating to a certain temperature for a specific heating cycle, the thermostat responsible for that particular heating cycle is the one that’s failing. However, if a dryer isn’t maintaining the proper air temperature for any of the heat cycles, the problem is likely related to another area of the dryer, not the thermostats.