How to Check the Door Switch
The door switch is a simple on / off switch to indicate whether the dryer's door is open or closed. The dryer will not operate when the door is open. If your dryer runs with the door open, the switch may shorted closed or there may be a dangerous electrical short in your dryer. If your dryer will not start when you press the start button and you hear no sounds, the door switch may be the problem.
Before checking the door switch, unplug the clothes dryer or shut off the power at the fuse box or breaker panel to avoid an electrical shock hazard. Turn off the gas supply to your dryer.
The dryer door typically has a prong the presses the door switch when the door closes. If that prong is damaged or missing, that may be the problem and not the switch itself.
The door switch may be accessible without removing the front panel or cabinet. The switch is located in the front panel of the dryer, around the perimeter of the door opening. Inspect the switch to determine if it can be popped out or accessed by removing a fastening screw. If it cannot be accessed from the front, it will be necessary to open the dryer cabinet. When reaching into the dryer be careful of sharp edges on the cabinet and interior supports.
Access varies by model, if your dryer has a lower front panel (kick plate) start there. It should lift up and off or it may be held in place with a few screws or snaps; it may also have a catch at the edges or center gap between the kick panel and main panel. To release the catch, push a putty knife, wrapped with masking tape, into the gap and push back the catch. The next easiest access point is the rear panel. The rear access panel is held in place with several screws along the outer edges. The last resort method of access is the removal of the entire front panel. The front panel supports the front of the drum and so removal is more difficult. Front panel removal varies. In general, access is gained by lifting the top (remove the lint trap screws first), removing the screws that secure the front panel, and detaching the panel from the drum.
Locate the start switch, it typically has two wires connected to it. Label the wires and connections so that you can properly reconnect them later. The wires are connected with slip on connectors. Firmly pull the connectors off of the terminals (do not pull on the wire itself). You may need to use a pair of needle-nose pliers to remove the connectors. Inspect the connectors and the terminals for corrosion. If either is corroded they should be cleaned or replaced.
Use a continuity tester or multitester to test for continuity. Set the multitester to the ohms setting X1. For a two wire switch, touch one probe to each terminal. You should get a reading of infinity. With the probes still in place, press and hold the switch, the reading should change to zero.
If the switch does test as described, it should be replaced.