Why Is My Microwave Whistling? Here’s Why + How to Fix

If your microwave is whistling, it might be on its way to overheating or burning out. There are many parts of a microwave that can cause strange sounds, all of which need to be addressed. A whistling microwave can make you have to replace yours, but it could also be related to a few minor adjustments.

Your microwave is whistling because the turn table is unlevel or it has worn, rusted bearings. A broken magnetron or an overloaded high-voltage capacitor with also make a microwave squeak and whistle. Check the rollers and fan blades to ensure they don’t wobble.

If you’re interested in fixing your whistling microwave, it’s important to check the turn table, fan, and capacitor. Those three main components are almost always the cause of the unwanted high-pitch sound.

The Magnetron Is Damaged

A damaged magnetron will prevent your microwave from heating properly. If this tube is broken, your food might feel colder than usual. You could also check your microwave’s voltage to know if the magnetron isn’t functioning as it should. If the voltage or wattage is lower than usual, it needs to be replaced.

Magnetrons often overheat or malfunction if the microwave fan isn’t working.

Similar to a tower fan burning, a microwave can catch on fire if the magnetron wears out.

How to Fix

Your best bet is to get a new microwave. According to Angi, the replacement cost of a microwave magnetron is the same as replacing the whole microwave.

The Toshiba Countertop Microwave comes with a built-in humidity controller that prevents rust, corrosion, and soggy food. It also has 12 preset menus, a manual timer, and an ultra-quiet turn table motor.

An Unlevel Turn Table

Your microwave’s turn table might not be balanced or level, which can happen due to the following issues:

• The turn table is missing one or more wheels.
• It’s not on the track, which makes the table shift.
• Too much weight is on one side of the turn table, shifting the rollers.

How to Fix

Follow these instructions to balance your microwaves turn table:

1. Remove the turn table from the microwave and clean the track.
2. Tighten each of the wheel screws with a screwdriver.
3. Place the turn table in the microwave and ensure its level (replace wobbly wheels).
4. If you have a mounted microwave, tighten the holding brackets.

Worn Microwave Bearings

Worn bearings can cause all sorts of problems, including loud noises. The subtle hum quickly turns into a screeching whistle, making your microwave unbearable to deal with.

Eventually, damaged microwave bearings can overheat and cause the motor to burn out. This also happens when plugging the microwave into an extension cord, especially if it doesn’t have a surge protector. You also shouldn’t use heating pads with extension cords.

How to Fix

Microwaves have fan motors and turn table motors. Both of these motors have bearings that allow the motor shaft to rotate, allowing the fan and the turn table to move.

Here’s how you can replace the motor bearings to stop your microwave from whistling:

1. Turn off the microwave and unplug it (or flip the circuit breaker).
2. Remove the screws from under the microwave for the turn table motor or behind the microwave for the exhaust fan motor.
3. Disconnect the hot and neutral wires from the motor, then pull the old motor out of the microwave.
4. Secure the new motor to the microwave after connecting the hot and neutral wires to it.
5. Attach the microwave cover to the back or underside of the microwave.

Watch this video guide to learn how to replace your microwave’s faulty motor:

Rusted Fan Parts

Every microwave has an exhaust fan to prevent excessive heat buildup. If the fan’s bearings, blades, or retaining bolts rust, they will whistle throughout the microwave.

Rusted fan components typically happen due to unknown spills, high humidity levels, and loose screws letting moisture into the fan parts.

How to Fix

If your microwave fan is rusted, you have to replace it. Follow these fan replacement instructions:

1. Unplug the microwave to remove the electrical current.
2. Remove the inner side panel or the rear panel from the microwave, depending on the model.
3. Unscrew the microwave and place a new bolt and fan in its place, then attach the old wires to it.
4. Attach the microwave panel, then plug it in and make sure the fan works when you turn it on.

Overloaded High-Voltage Capacitor

Most microwaves have high-voltage capacitors that are loaded with a lot of electricity. In fact, they even maintain an electrical current long after they’re unplugged.

High-voltage capacitors can experience short circuits and power surges that make them whistle. This is quite similar to low-voltage doorbell issues that make the appliance hum or buzz. Furthermore, an overloaded high-voltage capacitor can reduce a microwave’s display brightness.

How to Fix

Keep these tips in mind when changing the high-voltage capacitor in a microwave:

• Unplug your microwave when getting a different capacitor to stop your microwave from whistling.
• Discharge the capacitor using these discharging instructions.
• Always use a high-voltage capacitor replacement with the same electrical specs.

Note: Unplugging the microwave doesn’t remove electricity from the high-voltage capacitor. You have to manually discharge it.

For example, when you unplug a space heater, it still has a small amount of power going through it until it’s discharged.

A damaged capacitor will also stop a microwave light from working.

Excess Pressure on the Turn Table Rollers

If you have an old microwave with weak turn table rollers, putting too much weight in the microwave can make it whistle. The good news is that you can often replace the turn table to get rid of this problem, though you might also need to reduce how much food you put in the microwave.

How to Fix

So, what can you do if your microwave is whistling from excessive amounts of pressure? Try these suggestions:

• Keep all of your food and drinks in the middle of the turn table unless otherwise instructed by the food company.
• Don’t exceed the turn table’s weight recommendations.
• Upgrade your microwave’s turn table if yours is cracked.
• Replace the center plate O-ring or gasket to provide smooth rotations when your microwave is on.