Why Is My Microwave Making Noises – Troubleshooting Guide

You head to the microwave to warm food, only to be welcomed with a loud uncharacteristic noise. You’re sure the machine never produces this sound. So why now?

Typically unusual sounds indicate a problem that needs repair. But to correctly diagnose this “microwave making noises” situation and find an accurate solution, you must know what the different sounds mean.

Here, I’ll explore some atypical microwave sounds, their possible diagnosis, and how to handle them.

Microwave Buzzing or Humming

It’s uncharacteristic of a microwave to generate buzzing or humming noises frequently. These sounds might indicate the following problems.

Clogged or Worn Fan

The first possible diagnosis for a buzzing microwave is a worn or clogged fan. Sometimes, the fan gets dislodged, or debris accumulates around the fab bearing or axel. This can cause friction between the rotating parts, or the fan may clip against another component.

It could also be a sign that the fan is worn out and needs replacing. Typically, the cooling fan is audible during regular operation. But the fan motor could be problematic if the noise is excessive or the microwave produces a buzzing sound from the rear of the machine.

To access the fan, you must remove other components. Always exercise caution as you follow these diagnostic steps:

1. Disconnect the machine from the power
2. Discharge the capacitor
3. Take out any part that limits access to the fan
4. Check whether the fan spins freely. If it doesn’t, yet there’s no obstruction, you may have to replace the motor
5. Use a multimeter to test the motor’s continuity. The reading should be 280 ohms.
6. If the motor is faulty, replace it, or seek professional assistance to repair the failing part

Worn Diode

The diode could be worn out or faulty if your microwave produces a humming noise. This part converts AC to DC to supply the magnetron with power. You can test the diode using a multimeter and a 9V battery to determine if the diode has continuity.

1. Create a closed circuit between the multimeter and the 9V battery. Be sure to include the diode within the closed circuit.
2. The diode should show continuity in one direction. This signals the diode is okay.
3. If the diode shows negative continuity or continuity in both directions, it is faulty and will need to be replaced

Top Reasons Microwave Is Loud or Noisy — Microwave Oven Troubleshooting

Microwave Making a Clicking Sound

Strange clicking noises from your microwave can leave you worried. But this is a common issue with multiple possible causes, including:

A Defective Magnetron Tube

A flawed magnetron is the most probable issue if your microwave makes unusual clicking sounds. 

This tube uses high-current, high-voltage DC power that creates the microwave frequency for cooking. It should be almost silent. But if you notice high-pitched clicking, it could be damaged or burnt out.

It’s still safe to use the microwave at this stage, but the magnetron could be on its final legs and requires immediate replacement.

Fan Motor

A clicking microwave could also indicate a worn-out stirrer motor, the blue blade that turns slowly to deflect microwave energy inside the machine. It makes an unusual clicking and grinding sound towards the end of its lifespan.

Replace the worn-out stirrer motor immediately because your microwave can’t heat food evenly without a functioning stirrer.

Faulty Turntable Motor

Clicking sounds could also mean worn-out turntable rollers or motors, a common, easy-to-fix issue. Generally, you can access this section from beneath the machine. But if you can’t, you may have to remove the casing. You’ll then diagnose the motor using the following steps:

1. Unplug the device from the power
2. Remove the turntable plate and roller
3. Unscrew the motor panel
4. Use a multimeter to test for continuity. If there’s none, replace the motor

Microwave Making Grinding Noises

An abnormal grinding noise can indicate the same problems as a clicking microwave. The possible problems are

Faulty Turntable Motor

Though not common, this is a possible issue whenever you hear grinding sounds from your microwave. You’ll diagnose this common problem using the steps in the previous section. But if the issue doesn’t seem to be with the turntable motor, check the next possibility.

Faulty Stirrer Motor

A microwave’s stirrer motor ensures even cooking. So you cannot afford to overlook it if it has issues. Typically, the stirrer motor makes grinding sounds when it’s struggling to keep up.

Here’s how to diagnose this issue:

1. Unplug from the power source
2. Open the microwave cavity right above the turntable plate to access the stirrer motor.
3. Remove its cover
4. Check whether the blade is damaged or loose. You can disconnect it and then run the machine to find out if it still produces the same alien sounds
5. If it’s damaged, find a replacement

Microwave Making Rattling Noises

Another microwave sound you should be concerned about is an uncomfortable rattling. The possible causes of this issue include the following.

Faulty Turntable

The turntable should be the first area to check whenever you hear rattling from your machine. This uncomfortable sound sometimes results from positioning the turntable incorrectly. It could also be a result of defective rollers. You can diagnose this problem in the following ways:

1. Check whether the turntable plate and roller support are correctly installed
2. Find out whether the rollers have signs of tear and wear or if they’re clogged with debris
3. Ensure the food you’re trying to warm doesn’t overload the plate

It’s possible to hear rattling sounds even from a new microwave. If this is the case, check the machine’s bottom to ascertain whether the tape covering the shaft has been removed. If you notice any turntable plate or support damage, replace the sections. But if not, you’ll proceed to the subsequent diagnosis.

Obstructed Cooling Fan

A functioning microwave comprises different systems and parts that work jointly. For instance, the exhaust fan depends on the control board, touchpad, damper assembly, and fan assembly.

The cooling fan may stop working if any section within the functional path ceases operating or debris clogs the filters. Malfunctions can sometimes cause the fan to turn on but fail to go off. 

Loud rattling sounds may also be a result of a loose cooling fan. Fortunately, it’s easy to ascertain whether the noise comes from the fan because it produces a loud sound towards the back of the machine.

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Microwave Making a Popping Sound

A popping sound from your microwave could leave you fearing an explosion. However, this popcorn pop-like sound is typical and shouldn’t cause alarm. It’s usually a result of the food inside your microwave and not any defects on the machine.

High Water Content in Food

You’ll likely hear pop sounds if you’re preparing watery food. Usually, microwaves work by exposing the water molecules inside food to microwave frequencies. The pop sounds usually result from a rapid increase in temperatures.

High-Fat Content in Food

You may also hear scary pop sounds from your machine if you’re preparing oily food. Sizzles always accompany such food.

Food With Tight Covering

You’re likely to hear pop sounds when preparing foods with tight membranes, such as potatoes. This, also, shouldn’t scare you as it’s perfectly normal.

The best way to test these possibilities is by cleaning the microwave and conducting specific evaluations. You can try heating a water bowl inside the machine to see if it produces the same sounds.

To avoid or reduce these pop sounds, cover the food or pierce the tight skin of your potatoes before placing them in the microwave.

Microwave Squealing

Squealing is a common microwave issue with various causation factors. Here are the main possibilities:

Worn Magnetron

The first possibility when you hear a squealing sound is a worn magnetron. Sometimes, loud buzzing or humming noises accompany the squealing sound.

Here are the steps to access this part:

1. Disconnect the microwave from the power source
2. Remove the cabinet
3. Discharge the capacitor
4. Once you locate the magnetron, remove the mounting screws and disconnect the attached wires.
5. Before accusing the magnetron, confirm whether the high-voltage diode is shorted

Faulty Door Hinges

A squealing microwave door can drive you crazy whenever you open it. This may seem ordinary at first, but the sound can be too difficult to ignore after some time.

The problem mainly results from greasy vapors, humidity build-up creating corrosion, or continuous opening and closing leading to wear over time. Over time, friction can limit the door from operating freely. If left unaddressed, the hinge pin may bend, and some screws may loosen.

Microwave Making Noises When Off

A loose lower door switch is the most likely problem if the machine makes noise when not in use. This simple on/off mechanism prevents the microwave from functioning with the door open. The switches are mostly situated near the door latch and when faulty can cause a microwave to turn on by itself or fail to send power to operate the oven. As well as lead to electrical faults causing unusual noises.

Here’s how you’ll test them:

1. Set your multimeter to OHMS
2. Test the primary switch with the open door. Here, you’ll place the leads on the primary switch connectors. If the button is ok, you should hear a beep sound when you shut the door
3. You’ll then proceed to the secondary switch, which you’ll test using the same procedure as the first one
4. Next, you’ll test the monitor switch. The door should be closed first, and the meter should beep when you open it.
5. If you didn’t get the expected results with any of the three, replace the problematic one.

Notably, these switches supply the diode and magnetron with voltage to produce heat. So if your buttons test positive, it’ll indicate magnetron failure, and you’ll need to replace it if it’s not working.

Solved: Microwave Making Noises

The microwave oven is among the greatest time-saving appliances invented in the 20th century. But its indispensability is useless if the microwave is making noises that leave you annoyed or even frightened to use it.

These sounds usually signal an inherent problem that requires your attention. Fortunately, you now know what each sound could mean; hence, you can make an accurate diagnosis and find long-term solutions.

Always be cautious about electrocution when diagnosing or fixing your microwave. The machine has a high-voltage capacitor that stores dangerous electric charge levels even after unplugging. If unsure, you can take the safe route and involve a professional for diagnosis and repairs.