What NO HEAT Means
A no-heat fault means the microwave runs — the display works, the turntable turns, the fan operates — but the magnetron or its diode has failed, so food isn't actually heating.
Common Causes of NO HEAT
- Failed magnetron
- Failed high-voltage diode
- Failed high-voltage capacitor or transformer feeding the magnetron circuit
🔧 One Safe Check You Can Try
There isn't a safe at-home test for this — magnetron and high-voltage diode testing requires technician-level equipment and full power isolation.
⚠ Why You Shouldn't Go Further Than That
- The high-voltage capacitor in this circuit can store a dangerous, potentially fatal charge even when the unit is fully unplugged.
- Testing the magnetron circuit requires specialized equipment and training most homeowners don't have access to.
- Misdiagnosing which component failed (magnetron vs. diode vs. capacitor) means paying for the wrong, often expensive part.
- A damaged door seal or latch mechanism can, in rare cases, allow microwave radiation to escape during operation — a separate risk that requires specialized equipment to test.
- Built-in units require partial cabinetry removal to access these components, risking trim damage without the right technique.