If your microwave suddenly stops heating but still turns on and makes noise, there could be several possible reasons for this issue. Here are some common culprits:
Magnetron failure: The magnetron is the component responsible for generating the microwaves that heat the food. If the magnetron fails, the microwave will still turn on and make noise (such as the familiar humming sound) but will not produce the microwaves needed to heat the food.
Faulty high voltage capacitor: The high voltage capacitor stores the electrical energy that powers the magnetron. If the capacitor is faulty or damaged, it may prevent the magnetron from receiving the necessary power to produce microwaves.
Broken door switch: Microwaves are equipped with safety switches that prevent them from operating when the door is open. If one or more of these switches is faulty or not making proper contact, the microwave may appear to be functioning normally, but the magnetron won't receive power to heat the food.
Blown fuse: Microwaves have a fuse that protects the unit from power surges and electrical issues. If the fuse is blown, the microwave may still turn on and make noise, but it won't heat the food.
Defective diode: The high voltage diode is responsible for converting the electrical current from the capacitor to a high-voltage DC current that powers the magnetron. If the diode is faulty, the magnetron won't receive the correct voltage to produce microwaves.
Malfunctioning control board: The control board, also known as the main control module, is the "brain" of the microwave. If it is faulty, it may not send the proper signals to the various components, leading to a lack of heating.
Overheating safety feature: Some microwaves have a thermal cut-off or thermostat that shuts off the microwave if it becomes too hot. If this safety feature is triggered due to a malfunction or actual overheating, the microwave may stop heating.
Internal wiring issues: Loose or damaged internal wiring can disrupt the flow of electricity to critical components, causing the microwave to exhibit irregular behavior, including the lack of heating.
It's essential to note that microwave ovens contain high-voltage components that can be hazardous even when unplugged. Therefore, diagnosing and repairing microwave issues should be left to qualified professionals or experienced technicians to ensure safety and avoid further damage. If your microwave is not heating properly, it's best to have it inspected and repaired by a reputable appliance repair service.