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Microwave Ovens

Welcome to AP Wagner. You have come to the source for keeping your Microwave Oven and other appliances running like new! Below is some very beneficial information about how microwave ovens work, as well as what can go wrong with them. You will find answers to many common questions, and learn how to properly maintain your microwave oven. We provide many repair and service tips about microwave ovens. A handy do-it-yourselfer can use this valuable information to determine what's wrong with their microwave oven. The DIY can further use this knowledge to repair their microwave oven using the appropriate appliance parts. We provide a model lookup feature and an easy to use appliance parts finder to make your repair jobs easier. We also have appliance cleaning products, and an easy to use shopping cart.

The following information should help you repair your Microwave Oven. The information applies to most makes and models including: Admiral, Amana, Bosch, Crosley, Estate, General Electric, Gibson, Haier, Hardwick, Hotpoint, JC Penney, Jenn Air, Kelvinator, Kenmore, Kitchen Aid, Litton, Magic Chef, Maytag, Montgomery Ward, Norge, RCA, Sears, Sunbeam, Tappan, Westinghouse, Whirlpool, White-Westinghouse, and more.

Warning! Reduce your risk of personal injury or death. Disconnect your appliance from its power source before you start any troubleshooting or repairs. Danger of electric shock when working on electric appliances. Appliances have many razor-like machined edges; use caution when working inside any appliance.

How do Microwave Ovens work?


Warning! Microwave ovens carry high-voltage! Do not attempt repairs without taking the proper precautions. We do not recommend home repair of this appliance. Serious risk of injury and the risk of death come with opening up a microwave oven. There is a high-voltage capacitor inside this appliance. Warning!

Microwave ovens use microwave energy to cook or heat food. A microwave passes microwave radiation, at a common frequency of 2.45 GHz, which is equal to a wavelength of 12.24 cm, through foods. This radiation is really just a high frequency radio wave. The fat, water, and other molecules in the food act as electric dipoles. A dipole has a negative charge at one end, and a positive charge at the other. The dipoles try to align themselves with the alternating electrical field generated by the microwave radiation by rotating themselves. This causes a lot of bumping between the molecules, which creates heat by friction.

A common misperception is that food cooks from the inside out with microwaves. This is not true. The microwaves actually penetrate deeper initially, up to a couple of centimeters deep, than does the heat from convection and radiant heat cooking. This makes it appear that the food gets cooked from the inside out.

The cooking area is enclosed by a Faraday cage, which keeps the radiation safely inside the oven, and away from people and pets. The mesh you see on the door allows visible light to pass through, letting you watch the food cook, while blocking the microwaves. This can happen because the frequency of the microwaves is much larger than that of visible light. The legal limit of microwave leakage for new microwaves in the United States is 1 mW/cm² at 5 cms. This is way below the exposure limits thought to be harmful to humans.

When cooking or reheating foods in a microwave oven, especially a convection microwave oven, you need to allow at least 1" clearance between the food containers and all the walls and door. This will allow proper air circulation for optimum microwave performance.
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Common Questions about Microwave Ovens (FAQs)

Here are some common questions about Microwave Ovens

How can I repair chips and scorch marks in the microwave? There are many colors of appliance touch-up paints available. Arcing marks or chips in the finish are easily repaired with these paints. If arcing has occurred and you have a hole in the cavity, you can only safely use the microwave if the hole is smaller than one of the holes in the mesh screen. If the hole is bigger than that, you need to replace the unit because the microwave radiation (radio waves) may leak out past the hole.
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Why does my Microwave show the time but it won't cook anything? Microwave door switches are simple on/off devices that keep the microwave from running when the door is open. Microwave door switches are usually black and are about an inch long. They have metal terminals on the end that make contact with the door hook or latch. This completes the circuit which allows the microwave oven to run. Without this contact, the microwave will not operate. Check the door hooks and the door-release. If one of these is faulty, the door switch won't activate, and the oven won’t work. If you suspect that the thermal fuse has blown, call a professional appliance repair person. Even an unplugged microwave oven can kill or seriously injure someone. This is because there is a high energy capacitor inside the microwave oven case. If it is not discharged properly, you could be electrocuted.
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My Microwave is plugged in, why won't it do anything? If you have no power in the microwave, check to see if the outlet is good by plugging something else into it. If there is power, you may have blown the internal thermal fuse, or the door switch may be defective. Either of these will keep your microwave from working. The thermal fuse protects both you and the oven by blowing if there is too much power going through it. When a fuse blows, it means that the wire inside that conducts electricity has broken, usually because of an electrical overload. When it blows, you need to have a professional microwave repair person replace it. If this is not the problem, it may be that your door switch has become defective. If the door switch isn't working properly, it won't let the circuit complete to operate microwave components.
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Why can't I adjust the power setting? You may have a problem with the circuit board, or a defective triode. A triode is a diode for alternating current. Defective diodes will usually have a burnt smell, or may crack open or split. You should have a professional microwave repair person test it.

Sometimes a microwave won't respond if the programming sequence was not entered properly. If the touch control panel is unresponsive, check to see if delay start has been programmed in. Push the clear or cancel button. If this doesn't help, you can unplug the microwave from the wall for 30 seconds, plug it back in, and try again. The 30 seconds with no power may allow the panel to reset itself. Make sure the clock is set before attempting to program anything else.
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Why won't the turntable turn? If the turntable fails to rotate, open the door and look at the roller and ring assembly. Make sure that there is no food debris blocking the path of the wheels, and that the roller and ring assembly is seated properly. If not, it's pretty easy to re-align it. Sometimes though, the plastic coupler or the motor for the turntable may be defective. Other times the glass tray may jump off track. Simply re-seat the glass in the proper place. There are usually grooves in the plastic coupler that line up with grooves in the glass tray. To access the turntable, the cabinet needs to be opened. Some microwave ovens allow you to turn the turntable function off. Check to verify that it wasn't accidentally shut off. The last home check is to make sure you have pressed a cook function rather than a timed function. Call a professional appliance repair person if the case needs to be opened.
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Why does the display flicker? Sometimes the display on a microwave will flicker. A flicker can be caused by a power surge, sag, or brief power interruption. If the flickering doesn't seem to affect the way the microwave functions, it's probably okay to keep using it. You may want to use a surge suppressor with this appliance to help prevent any spikes or sags in the power supply. However, if the microwave is not functioning properly, and you think that the flickering is a symptom, you should call a professional appliance repair person.
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Why does my Microwave buzz or hum and not heat? A loud buzz from inside your microwave oven can mean that you may have a defective diode, triode, high-voltage capacitor, or even a faulty magnetron. This problem almost always means a bad magnetron, followed by a bad diode. Call a professional appliance repair person for assistance.
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Why did my Microwave stop working when I slammed the door? You can blow a fuse just by slamming the door. You may also have broken a door switch or made a connection come loose. Call a professional appliance repair person.
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Why do I see sparks inside my Microwave? If you see anything sparking inside your microwave, turn it off right away. There are a few reasons for sparks inside the microwave. One is that food or liquid got spilled and was not cleaned up properly. Anytime there is a food or liquid spill inside the microwave oven, it should be cleaned up as soon as possible. When cleaning the unit, turn off the appliance immediately, and unplug it. Another reason for sparks may be that there is metal in the cooking area. Do not use any metal dishes or utensils in your microwave. There may also be problems with an internal part that's defective causing an arc or spark. If you see burn spots inside your microwave, don’t use it until you have it examined by a professional appliance repair person.
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Are Microwaves dangerous? The government has rules concerning microwave oven leakage, so you don’t really need to worry about a microwave oven being dangerous to you. You get more exposure to these high frequency radio waves from a cell phone than from a microwave. The cooking area is enclosed by a Faraday cage, which keeps the radiation safely inside the oven, and away from people and pets. The mesh you see on the door allows visible light to pass through, letting you watch the food cook, while blocking most of the microwaves. It is rare that a microwave passes through the mesh, but it does happen occasionally. The incidence of this is so low that it poses no real danger to you. This is because the frequency of the microwaves is much larger than that of visible light. The legal limit of microwave leakage for new microwaves in the United States is 1 mW/cm² at 5 cms.
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Do things really explode in a Microwave oven? Yes, things can explode in a microwave oven. Things with a thick skin like potatoes, or with a shell, like eggs, can explode when cooked in a microwave oven. What happens is that as these things heat up, steam pressure builds inside of them. When the skin or shell can’t stretch or take the pressure anymore, they burst. An easy way to make a baked potato is to wash the potato, poke a few holes in it with a fork so that steam pressure doesn't build up, put it in a sandwich bag, and microwave it until it's nice and tender. Plastic works very well in a microwave, just be careful because the potato gets really hot!
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What kind of cooking utensils can I use? You do not want to put metal, wood, or Styrofoam into your microwave. Metal can cause sparking or arcing to occur inside the unit, while wood can actually burn, and Styrofoam can melt. You should only use microwave ready cookware. Never put gold trimmed plates in the microwave.
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Why isn't the fan running when I use my Microwave Oven? The fan cools down the magnetron and other electronic components. It is highly recommended that you do not run this appliance until the fan is fixed. Most fans are relatively inexpensive to replace.
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How do I clean my Microwave Oven? You can just use a damp soapy cloth to wipe it down inside and out. We also carry microwave specific cleaners in the cleaning section of our parts finder. Try to clean up any spills or splatters as soon as they occur. Do not get the controls wet! We carry a Microwave cleaner in the Cleaners section of our website.
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Can I use a browning dish in my Microwave Oven? Can I use a browning dish in my Microwave Oven? If you want to brown your foods, a browning dish is a good idea. This utensil simulates a frying pan and skillet. Follow the directions that your manufacturer has supplied. Most browning dishes require some pre-heating. Pre-heating times will vary for different size dishes and foods.

Precautions while using browning dishes include: Use the glass tray if your unit has one, start with the minimum time called for and increase as needed, use paper towels or napkins to dry meats as excess moisture hurts the browning process, and rotate the dishes.
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Why do I see steam coming from the door of the Microwave? Microwaves are not airtight appliances. If you see steam coming from the door area of your microwave, you're probably cooking or heating a high moisture food. Steam is allowed to escape to prevent overheating of the microwave. Furthermore, many times you will see condensation on the inside of the door or microwave. This is all normal. Just leave the door open for awhile to let it dry, or wipe it down.
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Why does my Microwave make a humming sound while cooking? If you hear a low humming sound while the microwave is running, it's probably the magnetron making the sound. Unless the microwave is set to high, the magnetron cycles on and off while cooking. Sometimes the cycling may sound more like a thump depending on your model microwave.

The other reason for a humming sound is because there is a transformer inside the case. This reduces power from the 110V feed to a level sufficient to operate the clock and light in the microwave. This particular humming sound will be noticeable when the microwave is not running.
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Is it normal to hear a fan running in the Microwave? You will probably hear a fan running anytime the microwave is on. This fan runs to keep the internal parts cool during operation.
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Why does my Microwave case feel warm during and after cooking? There are a couple of reasons why your microwave case feels warm during and after cooking. The biggest reason why the case heats up is that a lot of heat is generated by the magnetron. This becomes more noticeable the longer the duration of the cooking period. Another reason for the case to feel warm is that the food you're cooking radiates heat outward as it cooks. This extra heat should dissipate shortly after the microwave is turned off.
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Should I cover the food I am cooking in the Microwave? It's best to cover most food items. Covering your foods helps keep spatter from the foods contained. You can use microwave safe lids, wax paper, plastic wraps, or paper towels to cover foods. However, if you are browning a food, you don't want to cover it up with anything flammable like paper towels. If your microwave has food spatters on the inside, the spatters will absorb heat. This can lead to burn spots in the oven cavity.
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Can I heat up baby food in my Microwave oven? It is probably not a good idea to heat baby food in the microwave. If you do, be very careful not to over-heat the food. The microwave will tend to overheat the baby food as most baby food is pre-cooked and only needs reheating. Also, the baby food jars are usually not microwave safe.
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How can I tell if a dish is Microwave safe or not? There is a simple test to answer this question. Fill a cup with water. Place it in the microwave next to the cookware in question. Turn the microwave on high for one minute. If the water is now hot, and the dish stays cool, the dish is microwave safe. If the dish has gotten hot, the recommendation is to not use the dish.
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Why won't popcorn pop in my Microwave? If you're trying to pop popcorn, and it just won't pop, your microwave may not have enough wattage, or the popcorn may be stale. Microwaves need at least 500 Watts of power to heat popcorn enough to pop.
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Why do I hear popping sounds? Chances are good that these sounds are caused by the food you're cooking or heating. The popping can be caused by little bubbles of steam bursting or the fat on meat popping as it cooks. Clean up any spills or spatters. Popping sounds can also be caused by running an empty microwave. Never operate the microwave oven empty.

The use of metal objects in the microwave can be a direct cause of popping or arcing sounds. Make sure that you have the cooking probe inserted correctly.
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Why do I smell smoke from my Microwave oven? If you smell electrical smoke from a new microwave, it's most likely caused by the new circuit board heating up and curing. This should stop occurring after several uses.

If you have a convection microwave, and the smell is a dusty smoke smell, it is possible that there has been a dust accumulation on the convection heating element. This smell will dissipate as the dust gets burned off.

If there is a burnt food smell, you can open the door for a few hours to let any odors escape. We carry Micro Bryte® Appliance Cleaner on our website. Check out our other appliance cleaners while you're visiting us. Make sure to clean up any spills promptly.
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Why does my food over or under cook in the Microwave? You may be using the incorrect power level or time needed; your microwave oven door may not be sealed tight; or the Start button hasn't been pushed.
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What does error code PF mean? Error code PF simply means power failure. Code 8888 means the same thing. Push the clear button to reset the unit.
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Maintenance Tips for Microwave Ovens

Household appliances have average lifetime expectancies. Maintaining your appliances properly can extend their lifetime indefinitely.

If you have to do any kind of repair or maintenance on this unit, make sure to unplug it from the power supply.

Use a properly grounded outlet. Use a surge protector to protect this appliance from power surges as a surge can damage sensitive internal equipment. Some newer appliances have built in surge protection, and you should take advantage of these appliances whenever you can.

Clean the interior often to help ensure good microwave oven performance. Those food particles left inside still absorb the microwave energy and can cause interior burns to your microwave. Mild soap and water works well. We also carry microwave specific cleaners in the cleaning section of our parts finder.

Wipe down the outside touch panels with a damp, soapy cloth. Rinse the cloth with fresh water and re-wipe to remove leftover soap.

Do not heat food with foil wrapping. You may use paper towels or microwave safe lids to cover foods.

Never use metal containers to heat foods in the microwave.

Never run the microwave empty. You run the risk of damaging the magnetron and other components from feedback.
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