Microwave Making Noise? How to Fix It

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If your microwave is making noises, we hope after reading this article you will be able to find the source of the noise and fix the underlying cause. When you can hear a noise, it’s almost always due to one or more components in your microwave being defective. Sometimes this can be a component that is easy to fix, and sometimes it might require a more difficult repair to be made.

In this guide, we will describe the main noises people hear coming from their microwaves and then identify the part that is most likely causing it to occur.

Before progressing any further, we need to point out that working with the internal components of a microwave is very dangerous due to the risk of electrical shocks. Please don’t attempt any of these repairs if you’re not experienced and/or qualified to do so.

Microwave making a loud buzzing noise

If your microwave is making a loud buzzing noise, it might be caused by the magnetron. The magnetron produces the electromagnetic waves that cook your food or heat your drink when you put it in the microwave. When your microwave is running, you will usually hear a light, buzzing-type noise, which is caused by the magnetron. If that “normal noise” is much louder than it usually is or you can hear a high-pitched sound when your microwave is running, it’s probably caused by a faulty magnetron.

To check the magnetron, you need to:

  1. Switch the power to your microwave off, and unplug it from the power socket. If this isn’t possible, turn the circuit breaker off.
  2. Remove the top cover from your microwave.
  3. Locate the magnetron (if you’re not sure where it is, consult your user manual).
  4. Once located, discharge the capacitor.
  5. Test the magnetron for continuity with your multimeter.
  6. If the magnetron is faulty, it will need to be replaced, or you will need to purchase a new microwave.

Microwave making a loud humming noise

If your microwave is making a loud humming noise, the culprit could be a defective diode. The diode works with the magnetron and capacitor to power your microwave. Its role is to convert the alternating current into direct current so that your appliance has enough high voltage to provide power to the magnetron.

To check the diode, you need to:

  1. Switch the power to your microwave off, and unplug it from the power socket. If this isn’t possible, turn the circuit breaker off.
  2. Remove the top cover from your microwave.
  3. Locate the diode (if you’re not sure where it is, consult your user manual).
  4. Once located, discharge the capacitor.
  5. First, test the diode for resistance. The reading should be between 50,000 and 200,000 ohms. Second, test for continuity by reversing the meter leads. To be working correctly, continuity should only be in one direction.
  6. If the diode fails either of these tests, it will need to be replaced, or you will need to purchase a new microwave.

Microwave is making a rattling noise

If you can hear a rattling noise coming from your microwave, it’s most likely caused by a faulty cooling fan. The cooling fan can sometimes get loose debris caught in it or gets knocked around and ends up out of position. When either of these things happens, the fan can rub up against other parts of the microwave, and a rattling sound occurs.

Here’s how to check if the cooling fan is the source of the rattling noise:

  1. Switch your microwave off. If you cannot unplug it, turn the circuit breaker off.
  2. Remove the top cover from your microwave so you can access the cooling fan.
  3. Discharge the capacitor.
  4. Locate the cooling fan.
  5. Attempt to turn the fan around manually to see if anything is stuck in it. If it’s obstructed, remove the responsible objects. You can now put the top cover back on, plug it in, and test if the noise has gone.
  6. If the fan still doesn’t work or is not obstructed, test the fan with your multimeter for continuity.
  7. If the cooling fan fails either of these tests, it will need to be replaced, or you will need to purchase a new microwave.

Microwave making a clicking or grinding noise

If the noise you can hear coming from your microwave sounds like grinding, the turntable motor could be to blame. This motor helps the turntable to rotate; when it becomes faulty, it might start making a grinding noise.

Here’s how to check if the turntable motor is the source of the noise:

  1. Switch the power to your microwave off, and unplug it from the power socket. If this isn’t possible, turn the circuit breaker off.
  2. Remove the plate and roller from inside the microwave.
  3. Locate the turntable motor. It can usually be found underneath your microwave under a cover, or you might need to take the microwave cabinet/panels off and access it from the inside.
  4. Once located, test the motor for continuity with your multimeter.
  5. If the motor is faulty, it will need to be replaced, or you will need to purchase a new microwave.

Microwave making a grinding noise

Another possible source of a grinding noise is a faulty stirrer motor. This motor provides power to a metal blade in your microwave that is there to distribute energy around the microwave. When this motor becomes faulty, a grinding noise can develop.

Here’s how to check the stirrer motor:

  1. Switch the power to your microwave off, and unplug it from the power socket. If this isn’t possible, turn the circuit breaker off.
  2. Locate the stirrer motor, and remove the cover off it (you’ll find it inside the microwave).
  3. Inspect the stirrer blade to see if it has become loose or is damaged in any way.
  4. If the stirrer blade is damaged or loose, the whole unit (motor included) will need to be replaced, or you will need to purchase a new microwave.
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