How To Clean A Dryer Centrifugal Switch

When you push the start button on your dryer and you hear a humming sound coming from the motor area, it is not time to panic, yet. Yes it could be a defected motor but it is possible that the motor centrifugal switch is hung up.

A dryer centrifugal switch uses centrifugal force to open and close contacts on most dryer motors. When a dryer motor comes up to speed, weights on the dryer motor slide outwards taking pressure off the plunger on the centrifugal switch.

This allows the switch to open contacts to the start windings and close the heavy duty contacts for the dryer heater.

Sometimes when a dryer motor is covered in dust, the weights will hang up in the outward position. The dust prevents the weights from putting pressure on the centrifugal switch plunger closing the contacts to the start winding. A dryer motor can not start on the run windings alone so it will hum. Hold the start button long enough and you will burn up the run windings.

Another big problem with dust causing the centrifugal switch to be hung up is that the contacts to the dryer heater are closed. If the timer is moved from the off position to normal dry, the heater will be energized with the dryer not tumbling and the motor not running. This is a fire hazard.

So how do you fix a hung up centrifugal switch on a dryer?
It's actually very easy to clean a centrifugal switch on a dryer. Disconnect the dryer from the electrical supply and gain access to the dryer motor. Maybe you will get lucky and have a louvered access panel on the back of the dryer right behind the motor that can be removed. The access panel is usually held in place by two screws. The good news is that the dryer motor does not have to be removed from the dryer to clean the centrifugal switch. Take a vacuum cleaner that blows and completely blow the dust out of the motor. Switch back to regular vacuum and clean up all the lint in the dryer base area. Use your fingers to slide the weights back and forth on the dryer shaft making sure you do not knock off the springs. DO NOT lubricate this area as this will only attract more dust.