Why a Microwave Runs But Doesn’t Heat

June 16, 2020
Microwave Repair

Does your microwave turn on and appear to run its heating cycle only for you to open it up at the ding to find cold food? Certainly the most frustrating of situations, but actually it is really quite good news in a way. If a microwave were to just not run at all, it could be any manner of problems. However, a microwave that does run but doesn’t produce any heat can direct you to a more narrow list of potential problems.

Before we begin, you should highly consider leaving microwave repair to a trained professional. Unlike other appliances, a microwave can still hold a deadly charge when unplugged. The capacitors will need to be discharged and not everyone is comfortable doing that. In many repairs, you won’t be near the capacitors, but unfortunately, this repair will have you working directly near them and discharge will be necessary.

If your microwave is not producing heat, there are three primary culprits in the high voltage area of the average microwave.

  • Diode – Microwaves use capacitors to double the voltage in order to work. As such, if a diode is burnt out, it may still have the voltage to run, but not the voltage to produce heat. Luckily, you can spot a burnt-out diode easily as it looks like a burnt spot.
  • Door Switch – A microwave uses not just one door switch, but a series of them that are set to go off in a certain order to protect you. Unfortunately, if one door switch in the cycle goes faulty, the microwave may run, but it may prevent the heat from kicking in.
  • Magnetron – This can be the most dangerous situation. If your magnetron has gone out, it will not be able to produce heat. However, this also means that the capacitors are staying charged for a long period of time and this is dangerous. If you have troubleshot the other issues and believe it is the magnetron, this is definitely a job for a professional. Furthermore, as a magnetron replacement can be so expensive, it may be more cost-effective to get a new microwave instead.

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