Have not worked on this brand of microwave but with the door open I would expect to have two open circuit and one closed. The closed one being a back-up safety feature to blow the fuse if the others fail. The microswitches usually state on them N/C or N/O contact at the tag that is wired but you could always check continuity using an ohm meter with the unit unplugged. Beware of capacitor charge even although unplugged.