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Why Has My Microwave Exhaust Fan Stopped Working?

John Turpin is our resident home service repair expert here at Service Direct. He’s got the knowledge and experience to help homeowners like you make sense of most home repair issues. And with Service Direct, we connect you with top-tier service professionals to help with any repairs needed.

Learn How to Fix Exhaust Fans on Microwaves

Microwaves are an invaluable appliance that makes life a lot more convenient. But what do you do when you find the microwave exhaust fan not working?

Reheating food has never been so easy since the invention of this appliance. But microwave ovens are more than just that – they can be used in many ways, from steaming vegetables to sanitizing cutting boards and sponges.

Seeing the extensive use of microwaves, it’s not surprising for it to be frustrating when it doesn’t work right because something’s wrong with the exhaust fan.

Don’t worry, though. We’re here to help you understand what’s wrong with your microwave’s exhaust fan, and learn what to do with it. Read on to find out!

Microwave main parts detail view
Check out the list below for the most common causes your microwave’s exhaust fan may have stopped working.

Why Is the Microwave Fan Not Working?

When a microwave is not working properly, the exhaust fan is one of the first things to inspect. There are several possible reasons why the exhaust fan is malfunctioning, including oil and grease that could be clogging it.

It shouldn’t be that difficult to fix the problem with a microwave exhaust fan. But it helps to have some insight on what went wrong with your microwave in the first place. Let’s start by discussing which parts of the microwave could be causing the exhaust fan to stop working or not turn on.

Charcoal Filter

The oven air is blown back out by the microwave through the charcoal filter. It is the last step of the filtration process designed to recycle air. Thanks to the charcoal filter, the air that comes back into the kitchen is free from food particles, odors, and other fumes.

Over time, this filter gets clogged. When that happens, the microwave suffers from poor air circulation, preventing you from enjoying the food you make. Besides hindering foul odors, the filter ensures that the microwave exhaust fan is functioning right.

The problem with the filter is that it isn’t easy to wash or reuse. As such, it’s a good idea to have several extra filters in stock. We also suggest changing the filter of your appliance once a year at least.

You will find the charcoal filter at the back of the microwave. Some newer models are designed so the charcoal filter is easier to remove and replace. But some need you to unmount the appliance and remove its case to get to the filter.

Grease Filter

The grease filter is where the cooking fumes pass through, absorbing fats and oils when the microwave warms the food. It’s a metal filter, catching grease from the air as it rises above the microwave.

It is also one of the appliance’s components that ensure the exhaust fan is working efficiently. The grease filter makes sure of this by clearing oils and fats out of the exhaust system so the fan doesn’t get clogged.

It is reusable but can quickly get slimy due to grease. It also tends to clog so in the end, it is better to replace than scrub and reuse.

Microwave exhaust fan problems DIY fix
See our list of common repair tips for microwave exhaust fans.

Damper Assembly

The damper assembly is a microwave component designed to keep exterior air from getting into the exhaust system. It is some type of air valve, which may cause the exhaust fan to stop working if something’s wrong with it.

It is located within the fan in a flap that keeps the outside air out. This flap is either plastic or metal. It is usually spring-loaded, opening when the fan is on and closing when it’s off. The assembly could stop working if it’s jammed, cracked, or if a spring broke.

Our resident home repair guru, John Turpin, has provided a list of common reasons why your microwave’s exhaust fan may have stopped working, along with some suggested solutions and DIY tips to fix it.

Fan Motor

When the microwave exhaust fan is not working, most people’s first assumption is a broken fan motor. The good thing about this is that it has a direct solution – you will need to replace it with a new component.

The problem is it’s not that easy to fix. You will need to test the fan motor first to confirm if it is indeed broken or not. If the fan motor is indeed broken, the microwave has to be disassembled to put in the replacement part.

Follow the steps below to test the fan motor:

  1. Unplug the microwave and remove it from the wall.
  2. Remove the fan motor’s cover before rotating it manually.
  3. If the motor rotates, continue to remove it from the microwave.
  4. Use a multimeter to test it.
  5. Set the multimeter to Rx1, and then test the motor for continuity by touching its terminals with the probes.
  6. Look at the reading – if it reads 0, it means there’s continuity.
  7. If the motor doesn’t rotate or the reading doesn’t show it has continuity, it means the fan motor needs to be replaced.


If the over-the-range microwave fan is not turning on, one possible reason is due to a malfunctioning touchpad. It could be that the fan itself is fine and the only problem is with the button that activates it.

Most modern microwaves now have a touchpad. These are pressure-sensitive buttons used to operate the appliance. The buttons have some sort of depression mechanics underneath them that, when broken, could cause the exhaust fan to stop working.

The solution would be to replace the touchpad, which fortunately is not that difficult. It typically only involves removing the old front panel and switching it and the wire leads with new ones. After that, the microwave exhaust fan should start working once again.

Control Board

The problem with your microwave’s exhaust fan could be due to a failing control board. This component, located underneath the touchpad, is the appliance’s brain. It determines all signals and functions that the microwave does.

It goes on to say that if something is wrong with the control board, it could appear that something’s wrong with the exhaust fan. The faulty control board could be sending a signal so the fan starts even if the button wasn’t pressed.

If the control board is the issue, fixing it becomes a bit more complicated. This is because this is a delicate part of the microwave. Before replacing or trying to fix it, make sure to test it first with a multimeter.

Microwave exhaust fan repair tips
Each of these solutions could fix your microwave exhaust fan issue.

How to Fix an Exhaust Fan on a Microwave

Many different systems are involved to make a microwave work. As stated previously, the exhaust fan on your microwave could be malfunctioning for a variety of reasons.

Fixing a malfunctioning exhaust fan involves checking each one of the components we mentioned, and testing if they work or not. When you find the potential cause of the problem, then you can proceed to the next step of fixing the exhaust fan.

In most cases, it involves replacing the broken or faulty component. Also, it’s usually easy enough to replace them on your own. But if it’s the control board or if you don’t think you can handle it, don’t hesitate to contact an appliance repair technician you trust.

Microwave Exhaust Fan FAQs

Why Is There a Vent in Microwaves?

Vented microwaves are better at removing smoke and toxins, though not as much as a range hood. If you have a vented microwave, you can extract fumes and let them escape out of your house. Venting a microwave is important because it removes dangerous fumes building up in the kitchen, effectively preventing fires.

Should Vented Microwaves be Vented Outside?

Vented microwaves don’t need to be vented outside. There are, however, homeowners who prefer it that way. But even if your microwave isn’t vented outside, you have nothing to worry about from air recirculating in the kitchen as long as it’s not harmful fumes or smoke.

How to Improve Microwave Exhaust Fans?

You can keep your microwave exhaust fan at its maximum efficiency by making sure to maintain it properly. Do proper maintenance to the grease filter, charcoal filter, fan motor, and damper assembly, whether cleaning them or replacing failing parts. This is the best way you can keep the exhaust fan at its peak.

Hire a Local Appliance Repair Pro

The methods above are effective DIY tips to investigate, diagnose, and fix your microwave exhaust fan issues. But if you need professional help, then don’t hesitate to contact a local appliance repair pro using the phone number or form on this page.

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