When a microwave lights up, turns the plate and counts down but the food comes out cold, a component in the high-voltage circuit that generates the microwaves has failed.
Why your microwave is not heating
- Failed magnetron — the component that actually produces the microwave energy; the most common no-heat cause.
- Blown high-voltage diode or capacitor — these support the magnetron and fail with age.
- Faulty door interlock switch — a safety switch that, when faulty, can stop heating.
An important safety note
A microwave's high-voltage capacitor stores a dangerous electrical charge even when unplugged. This is genuinely not a DIY repair — it should be diagnosed and discharged by a trained technician.
Repair or replace?
For a basic countertop microwave, replacement often costs about the same as a repair. But for a built-in or over-the-range unit, a magnetron or diode repair is usually a fraction of replacement and saves matching a new unit to your cabinetry. Our microwave repair technicians will give you the honest comparison.
Microwave Not Heating — FAQs
Is a microwave that won't heat worth repairing?
For a built-in or over-the-range unit, usually yes — it is typically a failed magnetron or diode, far cheaper than replacing an expensive fitted microwave. For a basic countertop model, a new one often costs about the same.
Can I fix a microwave that won't heat myself?
No — the high-voltage capacitor holds a dangerous charge even unplugged. It is one appliance that genuinely should be left to a trained technician who can discharge it safely.