Why Your Microwave oven Isn’t Heating and What You Can Do About It

Microwave oven

Microwave oven: While the typical range or wall oven takes up the most space and offers the most options for baking and broiling, and while a toaster oven is useful for tasks such as reheating pizzas slices or heating up bread and rolls, neither can compare to the efficiency of a microwave oven.

Nothing beats a microwave oven when time is of the essence and you need to whip together a meal… that is, until you find that pressing the start button no longer causes it to heat.

Why doesn’t my microwave heat anything? Four paragraphs below, we provide seven possible explanations. Let’s take a look at how a working microwave warms up our meal first, however.

The fundamentals of using a microwave oven

Although they vary in size, design, and the amount of power that they put off, microwave ovens all function according to the same basic principles.

When the start button is pressed after a specific power level option and cooking time have been chosen, the control board of the appliance will send 120 volts of electrical current (AC) through a line fuse, a cavity temperature controller, and multiple door switches.

This occurs just before the current reaches a high voltage transformer. The direct current (DC) power output of the transmitter is converted to alternating current (AC) power by a high voltage capacitor, which also works in conjunction with a diode.

This process results in the voltage being increased to nearly 5,000 volts, which is the level required to power the magnetron in the appliance. The magnetron is responsible for generating radio waves, which then proceed to go via a wave guide on their way to the oven cavity.

Once within the cavity of the oven, the radio waves induce the water molecules contained inside the meal to vibrate vigorously, resulting in the generation of heat that cooks the food from the outside in.

In order to ensure that the food is cooked uniformly throughout the microwave, most models have a motorized turntable. This turntable rotates the food items through the radio waves.

Keep in mind that the heated water molecules will steam the food items while they are being cooked, which is the reason why bread has a tendency to get soggy when it is heated in a microwave (let the toaster oven take care of reheating bread products).

Because the high voltage components, while functioning, might produce a significant amount of heat, the control board will also transmit electricity to a fan motor in order to cool the appliance.

If the cabinet or oven cavity area of the microwave becomes too hot, one or more thermostats will turn off the power to the high voltage system to protect the microwave from overheating and damaging itself.

Why is the microwave oven not heating up?

If your spaghetti primavera comes out of the microwave as cold as it went in, these are the seven most probable causes:

  1. Burned-out diode – Because the diode doubles the voltage to power the resonator to heat the food, a burned-out diode prevents the magnetron from getting enough voltage to work. When a diode fails, it is often seen damaged. You may also use a voltmeter and a 9-volt battery to test the diode for electrical continuity – the presence of a continuous electrical route in the component. Keep in mind that the diode should only be connected in one way. If the diode tests “negative” or “positive” for continuity in both directions (with the multimeter probes inverted), it has failed and must be replaced.
  2. Door switch failure – Most microwave oven include three or four door switches that enable the microwave to start or heat after the door is closed. Even when the door is entirely closed, a faulty door switch might prevent the microwave from heating. As with the diode, you may use a multimeter to check the electrical continuity of each door switch to see whether one or more have failed.
  3. Malfunctioning magnetron – If the magnetron fails, the microwave will not heat. Again, you may use a multimeter to check the magnetron for electrical continuity to see whether the component is broken. For the component to function correctly, the reading should be less than one Ohm and the magnetron should not have shorted to ground. Because the magnetron cannot be repaired, a burned-out magnetron must be replaced.
  4. A malfunctioning high voltage capacitor will prohibit the whole high voltage circuit from operating since the capacitor works with the diode to convert and double the current provided to the magnetron. When a capacitor fails, it often bulges or leaks. Even if there are no apparent indicators of failure, you may test the capacitor using an analog-style Ohm meter or a capacitor tester to verify whether the component is capable of storing and releasing its charge, as well as whether it is working with an appropriate capacitance rating. Just make sure the capacitor is completely depleted before touching it (see below).
  5. High voltage transformer failure – The magnetron may not be receiving power from the high voltage transformer. When a transformer fails, it will often arc and emit a burning odor.
  6. Blown thermal fuse, cavity fuse, or thermoprotector – All three of these components are intended to turn off the microwave’s power if it overheats. Again, you may use a multimeter to check each component for electrical continuity to see if any have blown and need to be replaced.
  7. Defective main control board – Because the main control board governs the power supply to all microwave components, a faulty board might be causing the appliance to fail to heat. Because this is a rare occurrence, you should first verify and test the other possible problematic components to ensure they are operational before contemplating a control board replacement.

When fixing a microwave oven, always prioritize safety.

Be advised that fixing a microwave oven has a significant danger of injury or death due to the high voltage and high current it uses.

Be sure to turn off the power to the microwave before taking it apart. Because of the high voltage capacitors used in microwaves, we advise against anybody except trained specialists servicing or repairing the microwave.

If the microwave’s cover or shroud has to be removed for any reason, the capacitor should be drained shortly thereafter.

Even though most modern microwave models have high-voltage capacitors with an integrated bleeder resistor to discharge the capacitor automatically when power is cut, it is still a good idea to try discharging the capacitor by hand just to be sure.

It is possible to achieve this by shorting the capacitor terminals with the use of a screwdriver blade or a pair of needle-nose pliers.

Tools like screwdrivers and pliers should have insulated handles so that you don’t get shocked if they accidentally touch the terminals.

You can also watch this video for more understanding about microwave oven.

Repair Clinic is the best place to get factory-direct replacement components for your microwave oven.

Did you find that the diode or magnetron had burnt out during your troubleshooting? Maybe the capacitor is deteriorating or the door switch is broken.

After that, you’ll need to track out a compatible replacement component for your specific model of microwave. RepairClinic.com is the repair partner you need in this situation.

To access a complete catalog of replacement components, enter the microwave’s entire model number into the search box on Repair Clinic’s website.

It is possible to narrow down your search for the necessary component by using both the “Part Category” (such as “Diode, Magnetron & Resistor” and “Switch”) and “Part Title” (such as “Diode” and “Door Switch”) filters.

Repair Clinic offers free microwave repair help information in the form of part test results and step-by-step prescriptive videos, articles, diagrams, and schematics, and they stock OEM replacement parts that are compatible with the most popular models from GE, Samsung, Whirlpool, LG, Kenmore, Frigidaire, and Panasonic.



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