Many times I’ve had to replace this door latch assembly. Often it comes with the three micro switches you see in this picture courtesy of Reliable Parts, sometimes it does not come with them. The indication that this may need replacement is when the microwave blows fuses or trips breakers when the door is opened…

One common problem with over the range microwaves is that they seem to function normally, lights on, turntable spinning, but they do not heat. Often the issue lies in one or more of the three microswitches not being struck properly by the latch mechanism on the door. When I run into this problem I usually…

This is the plastic cage that holds the door switches from a GE microwave. There are typically three micro switches and when testing them with an OHM meter the top and bottom ones are normally closed while the middle one is normally open.