Fan stays on when door is open, door switches test good
We recently started having an issue with our 6 year old GE microwave (model # JNM1951SR1SS) where the fan stays on when the door is opened. It's an intermittent problem, but in the last day or so the fan stays on almost every time the door is opened (turntable doesn't turn).
I've been searching various forums, and it seems the part most likely to cause this problem is a faulty door switch. I've tested all three, and they all test good. Top and bottom are NC, and the middle switch is NO. All cycle appropriately when checking with a multimeter. I've removed the entire switch mount to check them, and I also checked them installed to make sure the door was making physically with the switch actuator.
We've also had rare issues with the reheat auto sensing function causing the microwave to go into error, but I'm not sure if it's related to the primary issue.
What else could cause the fan to turn on when the door is opened?