How to Fix the Operating Thermostat on a Dryer With a Bad Timer

The operating thermostat, also known as the cycling thermostat, controls the temperature inside the dryer. If the operating thermostat is not functioning properly, it will be unable to turn on or turn off the heater circuit for the dryer. This will cause your dryer to either run too long or not long enough. A defective thermostat will also fail to activate the timer motor, resulting in your dryer timer stopping mid-cycle and failing to advance.

What is an Operating Thermostat?

The operating thermostat is a switch in the dryer that works with the timer and controls the temperature inside the dryer drum on both gas and electric dryers that have an auto dry cycle. The operating thermostat can turn on the heat source and the timer motor when the temperature has reached the optimal level. Once it reaches a certain point, it will turn off the heating element to prevent overheating. When the temperature inside the drum drops below a certain point, the operating thermostat will turn the heating element back on.

Where is the Operating Thermostat Located?

The operating thermostat is typically located on the blower housing or another area in the airflow ducting.

General Location of the Operating Thermostat in a Dryer

How To Access, Remove, and Inspect the Operating Thermostat in a Dryer

1. Disconnect your dryer from the power for your safety.
2. Remove the rear panel on your dryer to access the thermostat.
3. Remove the wires connected to the thermostat.
4. Remove any screws holding the thermostat to the back of the dryer.
5. Inspect the thermostat for any signs of damage. If there is any damage present, it will need to be replaced. If there is no damage, you will need to test the thermostat with a multimeter.

How to Test the Operating Thermostat

1. Some cycling thermostats have multiple terminals. You may only need to test the outer terminals. If the reading fails, then the thermostat is faulty and will need to be replaced by with a new one.
2. Set your multimeter or continuity tester to measure continuity.
3. Place a probe on each of the thermostat’s terminals. If the thermostat is working properly, you should see a reading of zero or very low resistance. If the thermostat is faulty, you will see an infinite reading or very high resistance.

How to Install New Operating Thermostat

1. Check “How to Access, Remove, and Inspect the Operating Thermostat in a Dryer”, for instructions on how to remove the thermostat.
2. With the old thermostat removed from the washer, simply place the new one in the empty slot.
3. Install the screws to hold the thermostat in place.
4. Reconnect the wires to the thermostat in their correct position.
5. Place the rear panel of the dryer back on, and your repair is complete!

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