A microwave that runs without heating has an electrical fault in the high-voltage section. This is not a DIY repair.
The Magnetron
The magnetron generates the microwaves; when it fails, you get sound and light but no heat.
Fix: A technician safely discharges the capacitor and replaces the magnetron.
High-Voltage Diode or Capacitor
A failed diode or capacitor cuts power to the magnetron.
Fix: These store a dangerous charge and must only be handled by a professional.
Door Switch
A faulty door switch can let the unit run while disabling heating.
Fix: The interlock switches are tested and replaced as needed.
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