Microwave runs but does not heat food; turntable rotates and light is on, but contents stay cold

Critical safety warning: The high-voltage section of a microwave (magnetron, capacitor, transformer/inverter) can store lethal voltages even when unplugged. Do not attempt to test or replace these components unless you are trained and have proper tools.

• Basic checks only: Confirm that the timer counts down, the interior light comes on, and the turntable rotates. If all normal functions work but there is no heat, the fault is almost certainly in the high-voltage system.
• Door and power checks: Ensure the door closes properly and the unit is on a dedicated, properly grounded outlet.
• Listen for abnormal sounds: A loud humming, buzzing, or arcing sound when trying to heat can indicate a failing magnetron or high-voltage component.
• Professional service: High-voltage diagnosis requires discharging the capacitor and testing components under safe conditions. Contact a qualified technician to test and replace the magnetron, diode, capacitor, transformer, or inverter as needed.