How Dryer Timers Work

Even though more and more dryers today, both gas and electric, operate using electronic controls, there are still plenty of dryers out there that use a timer. Imagine a very long board about 3 feet long with a series of switches mounted to it with wires running into the back of the dryer. You could sit there with a watch or clock and turn certain switches on and off at appropriate times to perform separate functions within the dryer. And if you think about it, that is exactly what a dryer timer does. It is an electro mechanical device that uses levers on plastic cams to open and close switches sending electricity to different electrical components within the dryer. This way you don't have to sit there with a board and a watch. Below is a brief explanation on how dryer timers work.

Dryer timers are basically a group of switches bundled together that are switched on and off by cams controlled by a small electric motor. These switch contacts control different functions of the dryer.

Dryer timers control all the functions of the dryer. When the dryer turns off, how long the heater is on and how long the cool down cycle is, etc.

Dryer timers have small motors on the back. The motor rotates gears and cams that open and close switch contacts that control the loads in your dryer. A load is something that does work like a motor, heater, light bulb or end of the cycle buzzer.

When the timer is manufactured the amount of time each set of contacts will be closed is built in by the timer cams and gears. Service manuals contain a timer sequence chart that have a matrix indicating how long each contact will be closed during a cycle. Technicians use multimeters to measure for voltage across timer contacts. And only the timer sequence chart will tell when a particular set of contacts will be open or closed.