Dryer: Starts then stops

The thermal fuse is usually mounted on the blower fan housing. It detects the temperature of the air venting from the dryer to the outdoors and trips if the air becomes too hot. It typically trips if the vent tube is clogged or the exterior damper is closed. In an electric dryer, the thermal fuse shuts off the dryer when it trips. In a gas dryer, it prevents the dryer from heating, but the dryer still runs. The thermal fuse doesn't reset when the dryer cools and must be replaced if it trips.

The drive motor rotates the motor shaft, which in turn rotates the idler pulley, which rotates the drive belt that's wrapped around the dryer drum. The motion of these components causes the drum to rotate during the cycle. The drive motor also rotates the blower fan blade on most dryers.

A failing drive motor may shut off in the middle of a cycle then restart after the motor cools down. Replace the drive motor if it overheats.

The wire harness connections on the motor can be repaired, but the internal components on the motor cannot. If the drive motor doesn't run when voltage is applied to it, replace the drive motor.

The electronic control board governs the timing and execution of dryer functions. The wiring connections on the control board can be repaired, but the control board itself cannot. Replace the electronic control board if it's receiving voltage but isn't transmitting it to the dryer components, causing the dryer to not work. The dryer may start but then stop in the middle of the cycle if internal control board components don't detect sensor signals accurately. It can be difficult to determine if the electronic control board is the problem (unless you see burn marks on it) and it's an expensive part that can't be returned once installed; for that reason, have a trained service technician perform advanced diagnostics on control board before you replace it.

The timer on the control panel lets you set the drying time by turning the timer's control knob. A small motor on the back of the timer advances the timer during the cycle. The timer's internal cams open and close switches or contacts to operate the various electro-mechanical components in the dryer (mainly the drive motor and the heating element). Replace the timer if the contacts aren't working, the dryer won't start, heat or continue running, or the timer won't advance.

The dryer door switch detects whether the dryer door is open or closed. The dryer won't start if the door switch senses that the door is open. Or, the dryer might start then stop if the door switch fails during the cycle. If the switch reads the door as being open when it's shut, or if it allows the dryer to keep running when the door is open, replace it.

Some dryers have a motor relay, which is an electrically operated switch. The motor relay stays electrically closed to keep the drive motor running as long it receives the proper voltage from the electronic control board. When the voltage supply to the relay stops, the relay opens electrically to halt the voltage supply to the drive motor, which then stops. When a motor relay fails, the dryer motor stops running when you release the start button.

The door catch is the part of the door latch assembly that's usually attached to the front panel, but sometimes is attached to the door. When the door is closed, the spring-loaded door catch encloses and grips the door strike, which is mounted across from it. The tension of the door catch keeps the door from opening until it's manually opened. If the door won't latch closed and the strike is intact, replace the catch. If the door catch holds the door closed to start the cycle but can't continue to hold the door shut during the cycle to keep the dryer running, replace the door catch.

The dryer door strike is the part of the door latch assembly. It's usually attached to the door, but sometimes is attached to the front panel. When the door is closed, the door strike is pushed into the spring-loaded door catch mounted across from it. The tension of the catch keeps the door from opening until it's manually opened. If the door strike damaged, replace the strike. If the door won't latch closed and the strike is intact, replace the catch. If the door strike holds the door closed to start the cycle but can't continue holding the door shut during the cycle to keep the dryer running, replace the door strike.

Preventive maintenance for a dryer includes cleaning lint from the vent tube that runs from the dryer to the outdoors. Trapped lint can clog the vent, which creates a fire hazard and can increase drying times.

A clogged vent tube also can cause the dryer to overheat and trip the thermal fuse, causing the dryer to stop.

Check the power cord for damage and replace the cord if you see any break in the wiring insulation.

Clean the outside cabinet and the inside of the drum using a soapy washcloth. Wipe down the surfaces with plain water to remove soap residue.

Wash the lint screen with water and a soft-bristle brush to remove fabric softener residue that can build up on the lint screen, lead to longer drying times and even cause the dryer to overheat. Allow the lint screen to dry completely and then reinstall the screen in the dryer.