10 Reasons Why Your Microwave Keeps Overheating?

Are you struggling with the overheating microwave? Do you need help finding out what might be wrong? You are at the right place. 

A faulty magnetron, blocked ventilation, malfunctioning thermostat, or power surges will cause overheating issues in your microwave. If you are overusing it without a break, it will also cause overheating. In such a case, unplug it and let it cool completely before using it again. 

This guide will teach you the common cases of overheating in the microwave and possible fixes. So, keep reading. 

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Why does my microwave keep heating?

It is frustrating to confront an overheating microwave even when turned off. 

Last week, I was about to bake my favorite cake in my microwave, and I saw it was overheating more than usual. 

I immediately unplugged it from the electric outlet to see if it was getting back to normal. 

But it kept overheating even though I turned it off. 

I immediately consulted a professional and fixed the issue as soon as possible. 

Working with such overheating microwaves is unsafe because there are high chances of electrical hazards. 

While I consulted a professional, I learned the common causes and guidance to fix those issues. 

Here are the 10 common causes of microwave which keeps on overheating: 

1. Blocked Ventilation 

For any electric appliance, ventilation is an essential consideration while installing it. 

A microwave operates by electromagnetic radiation to heat or cooks food inside. 

The food is cooked or hated by absorbing the heat from electromagnetic radiation. 

Internally a microwave generates heat in the cooking area where the food is being placed. 

And the microwave will have an exhaust system to release all the stored heat outside. 

It will prevent overheating in the microwave and also ensures safe operation.

Ventilation is an important system to expel all the heat created inside the microwave. 

If you have placed the microwave in an enclosed space with no chance of ventilation, it will start to overheat. 

When you place the microwave in the enclosed area, heat will accumulate inside the cooking area. 

Overheating caused due to the accumulated heat will lead to damage to the internal parts of the microwave. 

The internal parts like the magnetron and control panel will be damaged if not shifting the microwave to a ventilated place. 

Check if you have placed your microwave in a ventilated place. 

If not, it may cause the issue of overheating. In addition to that, it will also lead to fire hazards. 

You must make sure there is enough ventilation while placing a microwave. 

2. Damaged Magnetron

Magnetron is an essential component of the microwave as it generates electromagnetic waves to heat the food inside the microwave. 

It uses a high voltage to generate the electromagnetic field inside the microwave, attracting the electrons to release as electromagnetic waves. 

The food content inside the microwave uses these electromagnetic waves to get heated. 

If the magnetron is damaged, it will cause the microwave to keep heating even after the cooking time has ended. 

It will also cause an uneven distribution of heat and result in a cooler on one side of the microwave and hot spots in the other area of the microwave. 

In the worst cases, a faulty magnetron will continue to heat the food even when you turn off the microwave. 

It will often result in the burning of food. There are even chances of fire if action is not taken to solve the overheating issue. 

A faulty magnetron will also damage the other internal parts of the microwave. 

Internal parts like the diode and high voltage transformer will be damaged when not fixing the faulty magnetron. 

Check if the faulty magnetron is causing issues in your microwave. 

In such a case, replace the magnetron with professional help. 

As a microwave is a heavy-duty electrical appliance, replacing the magnetron on your own is not recommended if you are not professionally trained. 

3. Malfunctioning thermostat

The thermostat is also a vital part of the microwave oven, which helps to monitor its internal temperature. 

It is designed in a way to shut off the power to the magnetron when it detects overheating in the microwave. 

If the thermostat is faulty, it will cause the magnetron to overheat, resulting in the overheating of the microwave. 

When a thermostat is faulty, a microwave displays a false reading and continues to overheat the food inside it. 

It will also cause a rise in temperature above the safety levels. 

It will also damage the other internal parts of the microwave and may even result in fire hazards. 

Check if the thermostat is faulty in your microwave. 

In such a case, replace the thermostat with the help of professionals.

If the thermostat is causing issues in your microwave, replacing it will fix the issue. 

4. Overuse

If your microwave is overheating, you may be using it for a prolonged period of time without any breaks. 

Overusing the microwave will lead to the excessive production of heat inside it. 

The excessive heat will start to build up, and in such cases, the ventilation system will not be efficient enough to expel heat from the microwave. 

When you have excessively used the microwave, it will cause damage to the magnetron. 

If a magnetron continues to heat without a break, it will not get time to cool down. 

In such a case, a magnetron will be damaged. 

Also, the other internal components of the microwave will begin to wear out due to overusing the microwave. 

Inspect if you have overused the microwave. If that’s the case, turn it off. 

Allow it to cool down and let the microwave be turned off for 4 to 6 hours to release all the excessive heat. 

If you are overusing the microwave without letting it cool down, internal parts will get damaged. 

If you overuse the microwave, you must do expensive repairs or replace the entire unit. 

5. Power Surges

Power surges happen when a power outage, lightning, or a disrupted flow of electricity occurs. 

During the power surges, there is an increase in the voltage of the current resulting in the fluctuation of current flow. 

Due to the spike in the electric voltage to the microwave, internal parts will be damaged, resulting in overheating. 

Especially the magnetron will be damaged by the higher voltage of electricity. 

You can avoid this using an uninterrupted power supply ( UPS ) with the microwave. 

In addition to the microwave, power surges will also damage other electrical appliances. 

During lighting strikes, turning off the microwave and unplugging it from the electric outlet is better. 

Check if power surges occurred in your local area recently, which would be causing your microwave to overheat. 

In such a case, take your microwave to a professional repair service to find out the right fix for it. 

Continuing to use the microwave in such conditions will cause fire hazards in your microwave. 

6. Faulty Fan

Every microwave has an in-built fan inside it to expel the hot air from it and draw the cool air into it. 

It will help to prevent excessive heat build-up in the microwave by maintaining the balance in the temperatures. 

If the Fan is damaged or broken, it may fail to expel the heated air from the microwave. 

Due to the excessive heat, air builds up inside the microwave, and internal parts like magnetron, the transformer will continue to heat.

It will result in the overheating of the entire appliance. 

A faulty fan will produce a loud noise while the microwave is running, indicating the issues. 

If you hear such a loud noise from the microwave, you must replace it. 

Not replacing the faulty Fan will result in internal damage to the microwave. 

You will have to replace the entire unit. 

Seek help from a professional to replace the Fan from the microwave before it causes fire hazards. 

7. Damaged Waveguide

Waveguide is the metal chamber inside the microwave that transfers the electromagnetic waves from the magnetron to the food content placed in the turn table. 

A waveguide is made with a material to do the reflection of electromagnetic waves on the food content. 

If the waveguide is worn out or damaged, it will cause holes in the metal chamber. 

Due to this, the electromagnetic waves will escape from the microwave. 

It will cause excessive heat build-up inside the microwave, resulting in overheating. 

It will also cause fire due to the escape of electromagnetic waves. 

Check if the waveguide inside your microwave is damaged or has holes in it. 

If that’s the case, stop using the microwave immediately and replace the waveguide to fix the issue. 

You must seek professional help to replace the waveguide, as not doing it properly will cause internal damage to the microwave. 

8. Incorrect Voltage

Microwaves are manufactured in a way to operate in the voltage range of 110-120 v. 

If the voltage supply is higher or lower than this range, it will cause overheating issues in your microwave. 

For example, if the voltage supply is high, the internal parts like the magnetron, diode, and transformer will overheat. 

When a low voltage is supplied, internal parts will not function efficiently, resulting in the overheating of the microwave. 

In such a case, the low voltage will cause the internal parts to work hard. 

Check if your microwave is connected to the electric outlet, which can supply the required voltage to the microwave. 

If not, it may be causing voltage fluctuations. 

Install the electric outlet with enough voltage to fix the issue. 

Seek help from a professional to fix the voltage issue in your electrical system. 

9. Dirty or Damaged Components

If some of the internal components, like the turntable, transformer, and diode, are dirty or damaged, it will cause an overheating issue. 

In such a case, inspect all the internal parts of the microwave for any dirt and debris accumulation. 

In such a case, clean all the internal parts to fix the issue. 

When the internal components are dirty or damaged, it will cause the microwave to work harder to maintain the temperature.

If you cannot inspect which internal part is causing the issue, you must seek professional help. 

10. Age

If all the causes mentioned earlier are not valid in your case, your microwave must be old.

The average lifespan of a microwave is 10 to 12 years, and if your microwave has crossed that period, it is prone to overheating.

In an old microwave, the internal parts may be damaged or worn out. 

In such a case, replacing the entire microwave is the best choice. 

Because even if you replace the faulty parts, your microwave will continue to cause issues. 

If you are still confused, consult a professional to see what would work for you. 

Final thoughts

Overheating in the microwave is the obvious sign that something went wrong with its internal components. When my microwave was overheating, the faulty thermostat was causing the issue. I analyzed all the causes and found the issue to fix it efficiently. 

It would be best to analyze all the common causes in the article to fix the issue efficiently. If any of these issues occur in your microwave, seek help from a professional to fix it effortlessly without any risk. 

If you decide to fix it yourself, turn off the microwave and unplug it from the electric outlet. And wait for 2 to 4 hours to let the microwave realize all the stored electricity to avoid injuries. 

What happens if the microwave keeps running?

If your microwave keeps running without not being able to stop, it indicates issues in the control panel of your microwave. It happens when the microwave control board fails to send signals properly.

What causes a magnetron to overheat?

A magnetron will overheat when there is excessive reflected energy. It happens when there is a poor load in the oven.

Reference: Microwave_oven Wikipedia 

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Jeniffer Smith

Hi, I am Jeniffer Smith, a housemaker and blogger, and I grew up in Shrewsbury, Massachusetts. I have been researching and fixing appliances and other things around the home and kitchen from a young age to help my single mother. Every time something went wrong, I couldn't rest until I fixed it. And ever since, I have enjoyed fixing things around my home, and I am always ready to help my friends and family with advice and hands-on help. Since we were always looking for affordable ways of fixing things, we rarely hired experts and tried to fix most things ourselves. That interest brought me to write for this blog, as I realized my knowledge could help many people trying to fix things around their homes on their own without spending hundreds of dollars.

2 thoughts on “10 Reasons Why Your Microwave Keeps Overheating?

  1. Excellent! Loved reading this. Moved into a 2 year old condo In Florida coming from Pennsylvania. I had kitchen aid and Jenn aire there, no problems! I moved here in August and fell for the pretty condo and the talk of all the upgrades. I did not look deep down into things. Cost lots to bring things up to par
    And my standards. Microwave just went. Code was control board but two visits later still broke. Microwave top inside was filthy and I felt it had something to do with the filth as we finally found the thermostat burned out. Reading your article I see that definitely was the possibility. Coming next week to try to fix it again.

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