Why is My Microwave Not Heating? (Quick Solutions)

Why is my microwave not heating

I also asked myself why my microwave was not heating a few months ago after it had served me for almost nine years.

It started malfunctioning, and one day it suddenly stopped working. After some investigation, I gathered possible reasons why my microwave was not heating.

The reason why is my microwave not heating is:

The diode may have burned out, the door could be defective, there could be a blown-up fuse, the magnetron could be malfunctioning, or maybe the microwave had simply grown old and could no longer continue functioning normally.

The reason why the microwave had stopped heating was due to old age. I had seen almost all the signs but wasn’t ready to admit it.

The best solution was getting a replacement rather than repairing the many damages and buying all the required spare parts to bring it back to life.

With this article, I share my knowledge on why my microwave is not heating, among other topics like How does a Microwave Work When Heating Food, the Causes of Microwave not Heating, How to Fix a Microwave that is Not Heating Food and more.

How Does a Microwave Work When Heating Food

With the help of magnetrons, microwave radiation is produced and causes intermolecular friction, causing the production of heat.

A microwave works by generating microwave radiation with the help of magnetrons. The microwaves cause intermolecular friction between molecules in the contents placed inside the microwave.

The more the microwaves bounce back and forth, the more the water molecules vibrate, causing friction that releases heat.

In the same way, microwaves work while cooking or reheating a meal; it is the same way it will work when microwave radiation gets a chance to escape into the outside environment. Suppose they get in contact with your skin; they will react with water molecules in your skin, generating heat and eventually causing serious health issues.

Causes of Why is My Microwave Not Heating?

As stated earlier, a microwave may have stopped heating due to a burned-up diode, a defective door, a blown-up fuse, a malfunctioning main control board, or old age.

1. Burned-up diode

A diode is a component in the microwave that powers up the magnetron tube to enable the production of microwave radiation. When it is damaged, the magnetrons receive little to no power, meaning there is no production of microwave radiation to ensure enough heat to cook a meal in the microwave.

2. A defective door

Your microwave may not heat due to damage to the door. It could be the door itself or the door switch.

Microwaves are designed not to run or turn on when the door switch is not properly holding. Use a multimeter tester on the microwave door switch to determine if it has stopped working due to a failure in electricity continuity.

3. Blown-up fuse

A microwave may stop heating due to a blown fuse or cavity fuse. They are designed to interrupt the power supply in case the microwave overheats. They can also be tested using a multimeter to determine the cause of your microwaves malfunctioning.

4. A malfunctioning main control board

The main control board is responsible for regulating the power supply in the entire microwave components. When it malfunctions, the whole microwave stops working.

It is not easy to point out where the problem comes from when it comes from the main control board. Unless you are a professional, do not try to fix it yourself.

5. Aged microwave

When your microwave has worked for you for at least seven years and above, there is a high chance it is reaching its expiration date. Expiration is inevitable; when it happens, the only solution is to get a new microwave.

How to Fix a Microwave that is Not Heating Food

Allow the microwave to cool and restart after a few minutes, use a multimeter to check the continuity of power, call for professional help or get a new microwave.

1. Allow the microwave to cool and restart

Smart microwaves are designed to shut down automatically when they overheat. Suppose that happens to your microwave, especially one that is yet to be used for a while, unplug the microwave from electricity and allow it to cool for a few minutes, then restart it again.

This strategy worked for me a few times in the past before old age caught up with it.

2. Use a multimeter to check the continuity of power

The only way to find out for sure if your microwave stopped working due to discontinuity of energy, a blown fuse, door switch, or high voltage is by using a multimeter tester. However, this only comes in handy when you know how to use it and where to put it.

3. Call for professional help

Not everyone is handy when it comes to electrical appliances. It is okay to seek professional help despite how minor a situation may seem.

Even after using your multimeter tester and realizing a particular fuse blew up, knowing exactly what caused the blowing up may be a challenge unless you are a professional. Knowing what caused a fuse to blow up is the best solution to your microwave not heating up food.

4. Gently shut down your microwave door

Do not rush to assume something is wrong with your microwave, try to shut the door gently and see. Maybe it just needed a little patience for it to work.

Also, try cleaning the microwave as often as possible to prevent the possibility of food particles obstructing the door from locking up appropriately.

5. Install a new magnetron tube

A magnetron tube will wear off eventually, depending on how long and often you use your microwave. Occasionally, it may need to be replaced, so ensure a professional does it for you.

How Much Does it Cost to Fix a Microwave Not Heating?

Repairing a microwave ranges from $100 to $200.

Repairing a microwave is something I had to do severally before it finally shut down in the end. Issues like replacing minor spare parts like a fuse cost me as little as $50.

Repairing or replacing a magnetron tube costs about $150 while repairing an entire control board of a microwave could cost as much as $500.

A table showing causes of microwave not heating and solutions on how to fix

Causes of microwave not heating How to fix it
Overheating  Shut the microwave for a few minutes and restart
Malfunctioning door switch  Firmly and carefully shut the door of the microwave

Replace the switches

Malfunctioning diode Replace blown-up fuse

Replace the diode

Warn out magnetron tube Replace the magnetron tube
Malfunctioning control board Replace the control board

Get a new microwave


What to Do When Microwave Suddenly Stops Working?

When your microwave suddenly stops working, switch it off and unplug it from electricity. Let the microwave cool for a few minutes before switching it back on.

This strategy may work if the shutting down is not frequent. However, if this happens frequently, consider calling for help from professionals who might identify where the problem is coming from.

If your microwave does not restart after giving it a few minutes to cool down, it is also wise to get in touch with a professional. Do not try fixing the problem alone if you are unfamiliar with fixing microwaves damages.

Faqs on Why is My Microwave Not Heating

1. What is the most common cause of microwave failure?

The most common causes of microwave failure are overheating and blown-up fuse. A fuse is the first part of a microwave to get damaged due to high voltage entry in the microwave. It cuts excess energy supply into the main board, preventing further damage.

2. Is it worth fixing a microwave?

It is worth fixing a microwave only if the problem is minor, like replacing a fuse. However, major issues like a damaged mainboard may be too expensive. In most cases, the best alternative is to get a new microwave.

3. What are common problems with microwaves?

The most common problems with a microwave are burned-out diode, defective door switch, blown-up fuse, malfunctioning magnetron, and old age.

4. Can a fuse cause a microwave not to heat?

Yes, when a fuse is blown up, it cuts out the continuous electricity supply in the microwave. Without energy, the microwave cannot run.

Final thoughts

My previous experience with my former microwave was evidence enough that a variety of things can make your microwave not to heat.  My microwave went through several damages, some listed in the article before it stopped working.

From my experience, I also learned that it is not all microwave problems that can be solved via repair; sometimes, microwaves reach a point they can longer function, and frequent repairs become more expensive than getting a new microwave.

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