Kenmore 66469 / 66462 / 66464 Microwave Oven Logo
Sandy Brill Posted on Nov 27, 2006
Answered by a Fixya Expert

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High pitched hum/buzz

My Kenmore Elite microwave (countertop model) is making a high pitched humm or buzz, almost can't hear it at all. It's louder when you open the door. It works just fine except the sound. We unplugged it for now. Any suggestions?

  • Sandy Brill Nov 29, 2006

    By high pitched I mean it's definitely a different sound than what it sounds like when it's running. When it's not running the sound is so high pitched it's barely audible unless you open the door and almost put your head inside.

    Since my first post, it is now making the noise when it runs too. It's not very loud, but certainly different from its normal sound.

    The sound may be about the same frequency as the beep, but not as loud when the machine is not running.

    My husband thinks it would cost less to replace it than to fix it. I hate to contribute to the local landfill, and would rather fix it.

  • Anonymous Mar 21, 2014

    Our Kenmore Elite 88523 buzzes very loudly with door shut. Putting a glass of ice cubes in the oven on reheat will be boiling with five seconds. It does not have the normal operating sound. Built in Malaysia, not a good thought.


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  • Kenmore Master 9,179 Answers
  • Posted on Nov 28, 2006
William Miller
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Joined: Sep 15, 2006

By high-pitched, you mean it is not that same frequency as when it's cooking? Is the tone near or the same as the beep you hear when you press a key? Please post a little more information so we can help better.

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My galanza microwave, air fryer, oven will not heat while using microwave and makes a terrible racket?

here are some items to check for troubled microwave
Bad Magnetron Symptoms What are some bad magnetron symptoms to watch out for?
The following is a brief list of some of the most common signs that your magnetron is about to give out:
Heating: Either the microwave is not heating up at all, or the heating performance has degraded noticeably.
Burning Smell: A burning smell (non-food related), may be an indication that elements of your magnetron are overheating. In this case, switch off your microwave immediately, and arrange for a repair or replacement.
Unusual Noises: All microwaves make a bit of a hum, but if it's become much louder - or sounds like unusual vibrations - your magnetron may need to be replaced. Watch out for a clicking sound as well - that's a tell-tale sign of a magnetron that's about to fail.

Is It Worth Replacing The Magnetron In A Microwave?

It really depends on the cost and age of your microwave. If it's somewhere between five and seven years old, you're in the right period of time for a replacement anyway.
There's little point spending good money on repairing or replacing a magnetron if the rest of the appliance is likely to give up the ghost soon anyway!

Symptoms of a Bad Microwave Diode? (Answered!)
A microwave diode is one of the most important components in the appliance. Without it, it's impossible to generate the heat required to heat foods and drinks placed in the oven cavity. Unfortunately, the component can go bad, so it's important to understand the symptoms of a bad microwave diode.
Generally, the symptoms of a bad microwave diode include sparking, buzzing and humming, and the appliance failing to heat. Running a continuity test helps to determine whether the diode has a problem. Getting a new diode for replacement is the solution if the current one fail the continuity test.

3 Symptoms of a Bad Microwave Diode The following table shows the summary of the symptoms of a bad microwave diode as well as what you can do to fix the problem:
Symptoms Solutions 1. Microwave buzzing and humming Inspect the diode, test it for electrical continuity, and replace it if it fails the continuity test. 2. Microwave not heating Start by inspecting the capacitor and magnetron because they may also be responsible for making the microwave fail to heat. 3. Microwave is sparking Locate the diode, inspect it, and test it for continuity. Replace it if there's no continuity. There aren't too many symptoms of a bad microwave diode. The most common ones include sparks & burning smells, the microwave not heating, and the microwave making humming & buzzing.

1. Microwave Starts to Have Heating Failures

Apart from a failed main control board, a faulty fuse cavity, a blown line or thermal fuse, and a faulty door switch, the high-voltage diode could also be the possible reason why the Whirlpool, Kenmore, GE, or KitchenAid microwave is not heating.
Your microwave failing to heat is a perfect sign of a faulty diode, which means you should get a new one for replacement.

2. The Microwave Starts to Pop Sparks

Sparks in your Kenmore, LG, Samsung, or Whirlpool microwave could be a sign that the high-voltage diode is defective.
Also, a burning smell from your microwave can indicate that the diode is bad. A burned-out diode can break into two, wear out, or short.
Immediately locate the diode in the cabinet next to the magnetron and replace it.

3. Microwave Starts to Make Noise

Your microwave could be buzzing and humming because the high-voltage diode is defective.
Apart from the diode, other components that can make your microwave make noise are the plate & drive motor, cooling fan, and magnetron.
Keep in mind that you can't repair a bad diode. You can only replace it with a new one.

Safety Warning

While repairing a microwave, the chances of falling into electrocution by the high-voltage capacitor even after unplugging the power cord from the socket are very high.
So you need to be very careful when doing the diode test.
To begin with, the high-voltage diode is located close to the high-voltage capacitor. In fact, one of its ends is attached to the high-voltage capacitor.
And as you know, a microwave capacitor carries high power voltages, which can be quite lethal. It is therefore important to start by discharging the capacitor before getting to the high-voltage diode.
Although the capacitor can store charge for a long time, touching both its negative and positive terminals with a metal screwdriver blade will drain all the charge in seconds.

Testing the Microwave Diode

Before you even attempt to replace the diode on your GE, Whirlpool, or KitchenAid microwave, do a functionality test to confirm your suspicion.
You can visibly confirm the diode is burned-out when you see physical damages.
In case there are physical damages, use a multimeter to test if the diode still has a continuous electrical path.
To test the diode for continuity:
Touch the positive and negative terminals of the high-voltage diode with the multimeter probes.
If the diode test negative for continuity on both of its sides, the diode has failed and will need a new one for replacement.

Microwave maiking loud noises

Tip #3: Weird Noises

. A high-pitched noise while the microwave is in use means there's a good chance the magnetron tube or diode is failing. If the exhaust fan or magnetron tube are the culprits, you will need to call a local appliance repair service.
DIODE HIGH VOLTAGE You might have an issue with the high-voltage diode if your microwave is generating an odd or loud whirring sound. This element, together with the magnetron and the capacitor, is a part of the high-voltage circuit. The cabinet needs to be taken out in order to get to the diode.

BUZZING AND HUMMING Most buzzing or humming noises are frequently caused by the fan motor, vent fan, magnetron, or any combination of these. This noise from routine operations gradually gets louder over time.
As the microwave oven warms up, the oscillation happens, and the fan helps keep the mechanical parts from overheating. You might need repairs if the volume of your microwave suddenly increases.
Try running the magnetron at a lower power setting while putting food inside to see whether the magnetron is the cause of your problem. This will cause the magnetron to switch on and off to maintain the proper temperature. If the magnetron is the issue, there should be less noise.
CLICKING NOISES Even though your microwave might not have a revolving plate, some models spin food using a glass turntable or plate. This component aids in ensuring even heating throughout your meal. However, occasionally clicking noises may result from this action.
If you constantly hear clicking, see if your glass plate, roller ring, or track needs to be cleaned. These are simple to clean with soap and water, but you might have neglected to do so. The location of the plate is what determines the other option, so be sure it is still on course.
POPPING As you prepare food or after spilling food, you might describe the sound of your microwave as popping, crackling, or snapping. However, these tones frequently come from dishes with significant water or fat content, particularly sauces.
POWERFUL SOUNDS When it comes to microwaves or other appliances, these noises continue to be the most alarming. You should replace your microwave if the device starts to make an electric-sounding noise called arcing.

If you notice that while using your microwave, the electricity flashes in addition to making a sound.

Stop using your microwave if this occurs and you notice a hole in the back o WHY DOES MY MICROWAVE MAKE A VIBRATING NOISE

There can be various reasons behind a microwave making vibrating noises. Some are given below.
POWER MOTOR Your microwave's drive motor may be malfunctioning if the turntable is making an odd noise. The majority of microwaves with glass trays turn the tray with a motor-driven coupler or a roller guide.
Access must be made through the bottom of the oven because the motor is normally found below the floor. Normally, a holding screw holds the motor in place, and two wires are connected to it as well. The motor must be replaced if it is creating a grinding sound.
its because it is now dangerous.
A loud humming or buzzing sound could result from a damaged magnetron
PUSH COUPLER If your microwave is making an odd noise, the drive coupler for the turning tray can be the cause. The majority of microwaves with spherical glass trays revolve around the tray on a roller guide using a motor-driven coupler.
A drive coupler with an offset center roller is sometimes used in models that employ a rectangular tray to move the tray guide from side to side. Remove the tray and roller guide from the oven for either style and then check the coupler. Before you can pull the coupler off the motor on some models, you might first need to remove the motor from the bottom.
ROLLER GUIDE If the turning tray in your microwave makes an odd noise while rotating, there might be an issue with the roller guide underneath the tray. A motor-driven coupler is sometimes used in microwave ovens with spherical glass trays to turn the roller guide.


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Kenmore Elite countertop microwave model 721.79153010 has no power, completely stopped working.

has an internal fuse. but you need to find out why it has blown, has it been making any funny sounds while cooking. ??

Everything works exept the heat. Thought we had a power surge a few days ago?

To allow us to help you effectively (at no charge), please post a NEW problem to FixYa, and please include your brand name and the full model number from the tag in or on the unit, your symptoms, as well as the answers to these questions:

- When you try to microwave are the inside light, internal cooling fan and turntable all working?

- Is there any unusual noise or is it louder or quieter than normal?

(A loud buzz, hum, or groan is usually a shorted high voltage rectifier diode, but a sound like gurgling into an empty coffee mug is one symptom of a failed magnetron, and yet the mag can be bad without that sound.)

We have a sound clip here of what a microwave should sound like when the cooling fan and high voltage section are working.

Note that a
full Sears/Kenmore model number has 3 digits, a dot, then 8 more digits, such as ###.########

Maytag CMV1000BAW microwave doesn't heat

Probably a bad mag, if the transformer goes bad it will draw a lot of amps and blow the fuse. If a mag shorts it just makes a more pronounced hum. Same with the rectifier. If you Ohm out the rectifier it should show open both ways as it is a really high resistance and the only way it would make a louder hum is if it shouts. so If it looks open it is probably OK, and probably bad mag. .

Works - but the sound has changed

Possibly, the "fault" was the buzzing in the first place! Buzzing is usually a cabinet vibration caused by magnetic fields from the "gubbins". If the buzzing should occur again, try pushing/ pulling/ poking the cabinet while the oven is running, you may find a position that causes the buzz to stop.
Another possibility is you previously had something else placed in close proximity to the oven.
If a rattling cabinet is the problem, either try to reposition something, or just ignore it!

Microwave no heat

The "HUMM" indicates a breakdown in the High Voltage Side. The loud "POP" was the breakdown. You have only four Components in the High Voltage side.

1. High Voltage Transformer. You can eliminate this as the problem. Why? If it was the problem it would have blown the line fuse, and would have given off a burned transformer smell.
2. High Voltage Diode. Usually will Burn or Pop when shorted, but will then OPEN the Circuit and there is no "HUMM".
3. High Voltage Capacitor.This is the Silver Can with the two terminals on top. It can SHORT internaly between the plates (the two terminals) and give the "HUMM".
4. Magnetron. This is my number one suspect. A SHORTED Magnetron.

Kenmore 721.63662300, 1200W

The magnatron is shorting and overloading the high voltage transformer which is complaining with a load noise. Worth fixing if you do it your self. Magnatrons cast about $40 wholesale. There are just a few varieties of them that fit almos all brands. Try

Constant Humm / Buzz but Works OK

I was going to suggest the low voltage transformer, but when you said it sounded like it was coming from the left side, that seemed odd. I have a stock transformer here I keep for test that is loud, but it works. Odd, eh?
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