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My Microwave's Making Noise

A noisy microwave is often caused by a worn fan motor, especially when you hear rumbling or squealing while the fan runs. If the noise is a high-pitched sound, growl, or loud hum during cooking, the magnetron may be damaged or nearing the end of its life. A failing high-voltage diode can also make the magnetron noisy, so test the diode before replacing the magnetron. On an over-the-range microwave, inspect the exhaust fan motor by checking whether the fan blades turn freely, then test the motor for incoming power and continuity. If the noise occurs as the tray rotates, worn rollers in the glass tray support, turntable roller guide, or turntable ring may be responsible. A grinding sound can also indicate a worn stirrer motor. These microwave repairs can involve opening the outer cabinet. The high-voltage capacitor stores a lethal charge even after the microwave is unplugged and must be properly discharged before interior work. Magnetron, high-voltage diode, and other high-voltage repairs may require a qualified technician if you are not familiar with capacitor discharge procedures. Enter your model number to find the exact replacement fan motor, magnetron, diode, tray support, or stirrer motor for your microwave.

01 - Microwave Fan Motor

The fan motor bearings can wear out causing a rumbling or squealing noise. If the fan motor is making noise when its running it will need to be replaced.
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02 - Microwave Magnetron

The magnetron uses high voltage, high current DC power to generate the microwave frequency that cooks the food. Under normal circumstances, the magnetron emits a low hum. However, if the magnetron is damaged or nearly burned out, it may begin emitting high-pitched sounds or growling noises. If the magnetron is noisy, this indicates that the magnetron is nearing the end of its life or might be defective. A defective high-voltage diode can also cause the magnetron to be loud. Before replacing the magnetron, first test the high voltage diode. If the diode is not defective, replace the magnetron. (Warning: The microwave oven c...an store a lethal amount of electricity in its high voltage capacitor, even after the microwave oven has been unplugged. Due to the high running voltage and the potential for electric shock, it is extremely dangerous to replace the electronic components in a microwave. Only a licensed technician should replace the magnetron.)
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03 - Microwave Diode

The diode converts the AC power output of the transformer to DC, doubling the voltage to nearly 5,000 volts. This high voltage powers the magnetron to heat the food. A failing diode can be responsible for a noisy magnetron. When the diode fails, it is often visibly burned out. Inspect the diode and if the diode is burned out, replace it. If inspecting the diode proves inconclusive, test it with a multimeter that uses a 9-volt battery or put a 9-volt battery in series with the diode. When the leads are reversed, the diode should only have continuity in one direction.
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04 - Microwave Exhaust Fan Motor

To determine if the fan motor is defective, remove the fan motor from the microwave and try turning the fan blades by hand. If the blades do not turn freely, replace the fan motor. If the fan blades do turn freely, use a multimeter to test the motor for incoming power and for continuity. If the motor has power but won’t run, replace it. If the motor does not have continuity, replace it.
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05 - Microwave Glass Tray Support

The microwave glass tray support is the component that sits under the glass turntable tray to support the tray as it rotates. Over time, the small rollers on the support can wear out and start making a noise as the tray turns. If you've determined the glass tray support is the source of the noise, the part should be replaced with a new one.
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06 - Microwave Stirrer Motor

The stirrer is a metal blade which slowly rotates inside in the microwave. As the stirrer turns, it deflects the microwave energy randomly throughout the microwave. As the stirrer motor wears down, it begins to make grinding noises. To determine if the stirrer motor is worn out, check to see if voltage is getting to the motor. If the motor has the proper voltage, but is noisy or won’t turn, replace it. (Note: Proper voltage can be determined by reading the label on the motor. Because the stirrer motor is a geared motor, the shaft will not spin freely.)
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Frequently Asked Questions

Why is my microwave making a loud buzzing, rumbling, or squealing noise?
How do I test a microwave exhaust fan motor that is making noise?
Why is my microwave making a grinding noise when the turntable spins?
What causes a microwave stirrer motor to make a grinding noise?
How do I find the correct replacement part for my noisy microwave?