Microwave Not Heating Food but Runs? Best Fixes

By John Adebimitan

The microwave not heating food but runs issue might seem like such a drag at first, especially when you need to make meals warm quickly. This article will discuss the issue, highlighting the most possible causes and best fixes for it.

Why Is Your Microwave Not Heating Food But Runs?

Your issue could be caused by the wrong microwave heat settings. You might’ve forgotten to change a previous heat setting that would not work for your current need. This could happen when your microwave is set to ‘keep warm’ while there is a frozen meal in it, making the food heat very slowly and leaving you thinking the microwave is malfunctioning.

Timer Settings

This issue could also be a result of your timer settings. Some microwaves allow you to set a timer, telling the microwave to cook at a preferred time. This is done so one can have a hot meal waiting by the time they return from work or school. If you have set a timer on your microwave, it will not heat until the set time.

Dry Food

Another reason one might face the issue is because they put in something that can’t be microwaved. Most people assume that a microwave is a super machine that heats everything. However, a microwave can only heat the water in food. Hence, it is unable to heat dry food.

Damaged Door Switch

The microwave not heating food but runs issue could also be caused by a damaged or malfunctioning door switch. When the door switch malfunctions, the microwave might still run but it won’t heat food.

The door switch is a safety mechanism that ensures the microwave door is completely closed before it runs. This is implemented in most microwaves to protect against harmful radiation, the door can become damaged if it is slammed often.

More recent microwaves are equipped with three or four-door switches but it takes just one switch to stop the microwave from heating food.

Burnt Out Diode

The “microwave not heating food but runs” issue could happen when the diode in the microwave is burnt. The diode is one of the components that supply enough power to the microwave to make it heat food. If the diode is damaged, the microwave will run but won’t have enough power to heat food.

Burnt Out Magnetron

A burnt-out magnetron could also cause the ‘microwave not heating food but runs’ issue. The magnetron is the heating element in the microwave, it is the component that controls heat production and when it is faulty, it could blow a fuse, causing other components in the microwave to malfunction.

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How to Fix the “Microwave Not Heating Food but Runs” Issue – fix 1

To fix your “microwave not heating food but runs” issue, the first step to take is to check the settings on the microwave. Ensure your previous settings are changed to support the current need. Next, ensure you have not set a timer that is preventing your microwave from heating. Check the delay timer and adjust it appropriately. Lastly, putting dry food in the microwave wouldn’t work because the microwave can only heat the water in food. So don’t try to heat something that cannot be microwaved.

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Fix 2: Troubleshoot the Door Switch

You should test the door switch in your microwave with a multimeter. When the door switch fails, the fan and stirrer might still work but the magnetron – which is the heating element of the microwave – won’t work. Follow these steps to troubleshoot:

  1. Check if the light in the microwave stays on when the door is shut. If it does, that means the door switch is the problem.
  2. Ensure the door is closed properly. If the door opens with a mechanical button, push that button down while closing the door, then let go when it’s closed.
  3. If the steps above don’t help, then you can proceed to test with a multimeter
  4. Disconnect the microwave from the power source
  5. Take off the cabinet on the microwave
  6. Locate the door switch and take it out
  7. Set the multimeter to Rx1, press the switch down to forge the closed door
  8. While depressing the actuator button, use the multimeter probes to touch the terminals on the switch
  9. They should read zero. If they don’t, you will need to replace the door switch. Take the microwave to a technician for a proper replacement.

When fixing the “microwave not heating food but runs” issue, we recommend taking the microwave to a technician to avoid causing more serious issues. Also, fixing a microwave yourself could prove harmful.

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Fix 3: Troubleshoot the Diode

When the diode is damaged, the microwave will run but it will not heat food. This is relatively easy to fix and can be easily identified by a buzzing or humming sound and a visibly burnt diode. You can start by testing the diode with a multimeter using the following steps:

  1. Disconnect your microwave from the power source
  2. Take off the cabinet on the microwave
  3. Locate the high voltage diode and take it out
  4. Set the multimeter to Rx1 and use the probes to touch the terminals of the diode
  5. Reverse the probes to test the other direction
  6. The diode should give continuity in only one direction. If it doesn’t, then it needs to be replaced. Take the microwave to a technician for a replacement.
  7. If it does, you should check if there is power supplied to the circuit. This would also require the attention of a technician

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Fix 4: Troubleshoot the Magnetron

A microwave that runs but doesn’t heat food might have a burnt magnetron. The magnetron uses a ton of energy and testing it without the proper precautions or knowledge can be dangerous.

To fix this, we strongly recommend taking the microwave to a technician as this is a more complex problem.

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