Lever microswitch, the type used for door and position sensing in appliances

Generic photo: Raimond Spekking · CC BY-SA 4.0

How to test a micro switch / door interlock (COM, NO, NC)

Micro switches are small snap-action switches used as interlocks in microwaves, dishwashers, dryers and ice dispensers. Most have three terminals: common, normally open and normally closed. Test both contact pairs in both positions.

Single source ~20 min easyBrands: All

Before you start

Unplug the appliance or turn off the breaker before opening panels or disconnecting parts
Take a photo of the wiring before removing any wire
Resistance and continuity tests are done with power OFF and the part isolated
Microwave high-voltage capacitor can hold a lethal charge after unplugging: discharge before touching anything inside

Diagnostic steps

Unlock all 6 steps with expected values

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OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work.

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