Dryer: Why won't my dryer shut off?

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 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.