Dryer: Why won't my dryer start?

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.

For dryers with mechanical controls instead of electronic controls, the push-to-start button starts the drying cycle when the user presses and releases it, by completing the voltage path through the drive motor. If the push-to-start switch isn't completing the electrical circuit to start the dryer, replace it.

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 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 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 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. Some dryers will restart automatically when the motor cools, but others require that you restart them. 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.

Unplug the dryer and remove the top panel to examine the belt from the top of the dryer. If it is broken or damaged, 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.

A 240-volt power cords connects to contacts on the terminal block in the back of the dryer. Replace the power cord if overheated loose or shorted wires melt the insulation, if damaged wires no longer complete the electrical circuit to the dryer or if prongs on the outlet cord plug become disconnected from the wiring.