About the Thermal Switch

• The thermal switch is only activated when the heat in the dryer increases close to a level that the dryer is in danger of overheating, often due to a component malfunction. Depending on your dryer model, the thermal switch either directs the heating element to stop producing heat or cuts the power supply to the dryer by tripping the circuit breaker for the heating element, and in some cases both occur simultaneously.
  
  

Overheating Causes

• A number of reasons can cause an electric dryer to overheat. For example, if the thermostat that monitors air temperatures inside the dryer malfunctions, the dryer has no way to monitor the level of heat inside the drum and, as a result, continues pumping more hot air in until the cycle ends or the thermal switch activates. In addition, too much lint in the dryer's exhaust system can block air from circulating in the dryer. As hot air builds inside the drum, the dryer is at risk of overheating. Finally, if the heating element malfunctions, it can generate more hot air than is necessary to dry clothes. The excess heat can rapidly raise the air temperature in the drum to the point that the dryer overheats.
  
  

Reset or Replace

• Unfortunately, you can't reset a thermal switch once it has tripped. The only way to return the dryer to full operation is to change out the blown switch with a new one. Until you replace it, the dryer will only partly function. However, before you replace the faulty switch, inspect your dryer for component defects to figure out what promoted the switch to trip in the first place. Make any necessary repairs to prevent the dryer from overheating again.
  
  

Switch Replacement

• Unplug the dryer from the electrical outlet. Consult your dryer's user guide for assistance finding the thermal switch. It's typically found in the vent duct collar or the rear cover panel. Remove either the collar or panel to identify a bunch of wires close to the hot air vent opening. Close to the wires you should see a small plastic component with two wires sticking out, which is the thermal switch. The component is usually white. Detach it from its wires, and reattach the wires to a new switch.