This is usually the most frustrating issue. Possible causes include:

• Faulty Magnetron: The magnetron is the heart of the microwave, generating the microwaves that heat food. If it’s defective, the microwave won’t heat.
• Blown Diode: The diode helps power the magnetron. If it’s blown, the magnetron won’t receive power.
• Door Switch Issues: Microwaves have safety switches that prevent them from operating when the door is open. If a switch is faulty, the microwave won’t start.
• High Voltage Capacitor Problem: This capacitor stores high voltage and releases it to the magnetron. If it fails, the microwave won’t heat.

This can lead to uneven heating. Possible causes include:

• Broken Turntable Motor: The motor that drives the turntable can fail.
• Obstructed Turntable: Food debris or other objects can get stuck under the turntable, preventing it from rotating.
• Coupler Issues: The coupler connects the turntable to the motor. If it’s worn or broken, the turntable won’t turn.

This can make it difficult to operate the microwave. Possible causes include:

• Membrane Switch Failure: The membrane switch is the control panel. If it’s damaged or worn, the buttons may not respond.
• Control Board Malfunction: The control board interprets signals from the buttons and sends commands to the microwave. If it’s faulty, the buttons won’t work.

While some humming is normal, loud buzzing, grinding, or rattling can indicate a problem. Possible causes include:

• Magnetron Issues: A failing magnetron can produce a loud buzzing sound.
• Roller Guide or Coupler Problems: These parts can wear out and cause noise when the turntable rotates.
• Fan Motor Failure: The fan motor cools the magnetron and circulates air. If it’s defective, it can make a loud noise.