The microwave is supposed to make noise. No microwave is silent and all microwaves create a soft roaring sound as the food cooks. The high-powered magnetron and the spinning plate both contribute to the sounds that your microwave makes. However, most people know the difference between a normal microwave noise and the unusually loud sound of a microwave when something has gone wrong.
If your microwave is scraping, rattling, or if the sound has increased by an unusual amount recently, then there is likely a damaged or deteriorating component inside the microwave. Unlike other repairs, this is an issue of a component in the microwave that is not working properly rather than something that has stopped working at all. Even so, the solution will usually be to replace whatever part is making the noise before it fails entirely or makes an even louder sound when your microwave runs.
Rattling Roller Guide
The first and easiest thing to fix is the roller guide. The roller guide in your microwave is the ring or multi-armed piece of plastic with small wheels on it. This guide sits just below the plate, holding it up and providing a well-supported. If the roller guide is damaged or if the wheels are clogged with gunk, then additional rattling will be added to the sound of your microwave. This sound can be amplified by the fact that the roller guide shakes the plate. A plastic plate is resonant, while a glass plate is more likely to make a pervasively high-pitched rattle.
The roller guide is an easy piece to replace because it comes right out without taking apart the microwave. With the correct replacement part, you can simply swap it out with the previously damaged roller guide. If your roller guide is rattling because of grime, a quick soak and scrub will fix your problem.
Shaking Drive Coupler
The drive coupler is the piece of plastic attached to the turntable motor. The drive coupler attaches to a slot in the underside of the plate and spins the plate around. Just like the roller guide, if the drive coupler is damaged, it can cause the plate and the entire spinning mechanism to shake and rattle. This adds an additional problem in that the drive coupler is attached to the turntable motor. When the drive coupler is cracked or otherwise damaged, you will need to detach it from the turntable motor and the plate in order to remove and fix it. Sometimes, the coupler can be repaired but for the most part, it’s a good idea to replace this small, essential plastic component.
Grinding Turntable Drive Motor
If you hear a grinding sound coming near the bottom of the microwave, this can indicate that it’s a problem with the turntable motor, also known as the drive motor. As you can easily guess, the turntable motor is what provides the force to spin the turntable inside the microwave. It connects via the drive coupler to the plate. Like any motor, the turntable motor can make a real racket if it partially breaks yet continues to spin. Grinding, scraping, or unusually loud roaring sounds are common when your issue is a broken or breaking turntable motor.
Noisy Exhaust Fan Motor
The next thing to look at is your exhaust fan. This is a fan that keeps the air moving through your microwave and controls the amount of heat inside the mechanism. The fan motor is what spins that fan blade. Like the turntable motor, when a motor stops working correctly it can become extremely noisy. Fans can also make extra noise if one of the fan blades is damaged and begins to scrape as the motor turns. You can open up the back of your microwave to access and replace the exhaust fan.
High Voltage Diode
When electricity is not passing through the microwave the way it should, you will get a louder humming sound or even a high-pitched sound for those who can hear it. This can indicate that your high voltage diode is not working correctly. The high voltage diode works in conjunction with the magnetron and the high-voltage capacitor (the most dangerous part of the microwave) to create heat inside the chamber. As the name might suggest, the high-voltage diode and it’s paired capacitor should be treated with extreme care and may carry a charge after the microwave is unplugged.
The magnetron is the central component of the microwave. It is also the most expensive to replace. The magnetron usually emits a low hum, contributing to the primary sound of the microwave other than the turning fan and drive motors. However, if your magnetron is old or malfunctioning, this hum will become much louder and can be intrusive on your kitchen experience. If you or a repair technician confirm that the magnetron is your problem, often it is more cost-effective and efficient to replace the microwave entirely instead of replacing the magnetron specifically.
Scraping Stirrer Motor
Last but not least is the stirrer. The stirrer is a metal rod that spins near the magnetron. It mixes the micro-waves emitted and helps to more evenly distribute the heating effect throughout the chamber (and food) in the microwave. Like any moving part, the stirrer can become damaged and then start to scrape its way around the usual spinning path. If you hear a scraping sound that is not related to the turntable motor or components, it may be the stirrer inside the microwave cabinet. This part is tricky to replace, but not costly to source, unlike the magnetron. —When your microwave becomes noisier than usual, this is often a sign that one or more components have stopped functioning properly. The correct solution is to hunt down the problem and see if there is a reasonable fix. The trouble with the drive motor and turntable components are more approachable than trouble with the magnetron or high-voltage components. Remember to call a repair technician if you are not confident in safely performing a repair yourself. Also remember that even after you unplug the microwave, the high-voltage capacitor usually still holds a dangerous charge if contact is made.