A microwave that runs but won't actually heat has an electrical fault somewhere in its high-voltage section — this isn't a repair to attempt yourself.
The Magnetron
The magnetron is what actually produces the microwaves; once it fails, you still get the light and the sound, just no heat.
Fix: A technician safely discharges the capacitor first, then replaces the magnetron.
High-Voltage Diode or Capacitor
A failed diode or capacitor cuts off power to the magnetron entirely.
Fix: These parts hold a dangerous charge and should only ever be handled by a trained professional.
Door Switch
A malfunctioning door switch can allow the unit to run while simultaneously disabling the heating circuit.
Fix: The interlock switches get tested and replaced as a set if needed.
Not sure what's wrong? Book online — every visit includes a free diagnosis.