The drive motor turns the drum and the blower wheel to exhaust the air. Before replacing the motor, first check the thermal fuse, start switch, and door switch. If all of these parts are working properly, but the motor is making a humming noise, remove the belt from the motor and check the blower wheel for obstructions. If the blower wheel is clear of obstructions, the dryer motor might be at fault. If you suspect the motor is defective, replace it.
On most dryers, when the dryer belt breaks, the motor will still run, but the drum won’t turn. However, some dryers have a switch that shuts off power to the dryer if the drive belt is broken. If this switch fails, it could shut off power to the dryer even when the belt is not broken. First, start the dryer and then listen for a humming noise. If the dryer makes a humming noise when you try to start it, this indicates that the belt switch is not defective. Next, search for your model number to determine if your dryer has a belt switch. If your dryer has a belt switch, use a multimeter to test the switch for continuity. If the switch does not have continuity, replace it.