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Fan comes on light comes on and turntable spins when you open the door

HI, What is the make and model number of the microwave? Check if the door interlock switches are operating OK electrically with an Ohmmeter and usually there is also a door monitoring switch as well i.e. 3 switches. Be safety aware when working in a microwave oven. Depending on your medical condition It can be lethal. Correctly and safely discharge the HV capacitor before working in the oven. If you don’t know what you’re doing then leave it to the experts.