Dryer Will Not Start - Motor Hums

Most of the time there are two conditions that you will find when you have a dryer that will not start. You either have a dryer that the motor hums, or it will be silent when you push the start button. First let's talk about a dryer that hums when you press the start button. When a dryer motor hums, or makes a growling noise when you push the start button, most of the time the problem is going to be with the motor. The best thing for a non-experienced person to do at this point, is to unplug the dryer from the electrical supply. Gain access to the motor and inspected closely with the flashlight. If you find that the motor windings are burned, you need to replace the motor. If you are lucky and the motor windings are not burned to a crisp, hopefully the motor is covered in dust.

There are a lot of things that can cause a partial circuit but the result is the same as the stranded wire example. Many a heater or dryer motor has been changed needlessly because of a loose connection in the fuse box / circuit panel or some other dryer electrical circuit problem. If this is the case you're in luck. Carefully inspect the motor centrifugal switch slide on the motor shaft, under the centrifugal switch. Most likely you will find that it is hung up and not sliding back to where it normally rests when the motor is stopped. What you were hearing when you pressed the start button, was the motor attempting to start on the run windings, because the slide mechanism did not slide backwards to close the contacts on the centrifugal switch for the start windings. At this point you can use low-pressure compressed air, maybe the outlet air from a vacuum cleaner, to blow the dust out of the motor. Once you have done that, take the slide on the motor shaft and move it back and forth. Whatever you do do not use any lubricant thinking that will help it slide. The lubricant will simply attract dust and gum up the works again.

In the case of the dryer that is not making any sound when the start switch is pushed, you must first confirm that you have electricity to the dryer. Once you have confirmed that it's not the dryer electrical supply, the most likely component to fail, is the dryer thermal fuse. A dryer thermal fuse is designed to open the circuit to the motor in the event that the dryer gets too hot.

The number one cause of the dryer thermal fuse opening is a vent restriction. If a vent on the dryer is restricted, the air cannot exit the dryer. If the air cannot exit the dryer, the dryer control thermostat can not function properly. When this happens the dryer heater will cycle on the high limit thermostat. But that temperature is way too high. Sometimes as high as 220 degrees. When this happens the dryer thermal fuse, does its job and opens the circuit to the motor, shutting the dryer down. If you find that you have a dryer with an open thermal fuse, it is imperative that you check the vent for a restriction. Obviously if the vent restriction is not corrected, the dryer thermal fuse will just fail again. The easiest way for inexperienced person to check a dryer thermal fuse, is to use an ohmmeter. A dryer thermal fuse is a normally closed circuit, and will read zero when you checked the resistance.

The next likely defective component on a dryer that does not start, is the dryer door switch. A dryer door switch is designed to open the circuit to the motor when the dryer door is opened. It is a safety device, and as such should never be eliminated from the circuit. If you find that you have a bad dryer door switch, you must replace it. The way to check a dryer door switch, is to use an ohmmeter, and check the resistance of the contacts, looking for continuity.