Microwaves are one of the most common appliances you will find in the kitchen. They heat food and drinks quickly and are invaluable to any functional kitchen.
While there are many different brands of microwaves, Whirlpool remains one of the most popular thanks to their reliability, slew of useful cooking features, and reasonable pricing.
But these machines are not perfect, and many users have reported encountering an issue where the exhaust fan won’t turn off, even though the machine isn’t in operation. Not only is this loud and annoying, but it may also indicate a problem with the machine that needs fixing.
If this is happening to you, you’re in the right place. In this article, we’ll explain why this happens and how you can solve it quickly.
Why won’t your Whirlpool microwave fan turn off?
The primary function of a microwave oven is to produce heat through microwaves which warm up your food.
While there is a special lining inside the microwave oven to help protect the microwave itself from heating up, it will inevitably get pretty hot after some use.
So to stop the microwave’s sensitive electronic components from getting too hot, an inbuilt thermostat monitors the temperature of the microwave.
When this temperature exceeds a certain threshold, it will automatically turn on a venting fan which helps dissipate the excess heat and protect the microwave’s components from getting too hot.
However, there are reasons beyond just heat that will cause the fan to continue running. Many of these are due to malfunctioning components which need replacing.
Here’s a rundown of what will cause the fan not to turn off.
1. The microwave has been used for too long
Whirlpool microwaves are kitted with special shielding called a ‘Faraday shield,’ which keeps the microwave radiation inside the cooking area.
This mainly stops the microwave from cooking and only heating up what’s placed on the cooking plate.
However, even with this shielding, it will inevitably heat up if you use the microwave for prolonged periods.
This is caused by general heat buildup due to the cooking process and the heat produced by the components as the electricity runs through them for a long time.
Once the thermostat detects the microwave is too hot, it’ll kick on the fan to lower the heat and protect the microwave.
But more importantly, it will not turn off until the temperature is brought down, even though it’s not in operation.
2. The ambient temperature is too hot
Kitchens, in general, can produce a ton of heat, you may have multiple gas stoves in operation and a pot of boiling water going. Just through natural cooking, the kitchen can get hot.
Combine that with a hot summer’s day, and it’s easy to see how the ambient temperature in a kitchen can contribute to how hot the microwave gets.
So once again, as soon as the thermostat detects it’s too hot, it’ll turn on the fan until the temperature is lowered.
3. Clogged-up air filters
As we cook food or ingredients in the microwave, they can give off steam and other fumes we don’t want the venting system pushing into our kitchen.
So most microwaves implement a charcoal or carbon filter designed to catch all the impurities from the microwaved food, so it only pushes nice, clean air into our kitchens.
Over time these filters will become increasingly blocked until they physically can no longer push enough air through the filter to keep the machine cool.
This results in the microwave heating up, which will then cause the thermostat to kick on the fan again. Cleaning or replacing the filter can increase the air flowing through the microwave, which helps it stay cool.
4. Clogged-up grease filter
Used in a very similar fashion to the air filter, the grease filter is designed to catch grease, oils, and fat released from the food as it cooks.
Like the carbon filter, this builds up in the grease filter, further contributing to the restricted airflow, resulting in an overheating microwave.
5. Defective damper assembly
The damper assembly helps to direct airflow through the microwave to ensure the air passes correctly through the vent duct.
Depending on which microwave model you use, these can be made of plastic or metal.
When these malfunction by either warping, bending, getting kinked, or blocked, the air will not flow correctly through the microwave, which in turn causes it to heat up.
6. Faulty thermostat
The thermostat is designed to only turn the fan on after the temperature has reached a certain threshold.
So when the thermostat breaks, malfunctions, or short-circuits, it may turn the fan on even though the temperature has not exceeded the threshold.
Fixing or replacing the thermostat it will make the fan operate normally again.
7. The fan motor has broken
If the fan motor has malfunctioned and is no longer communicating with the thermostat, it may stay running indefinitely.
Fixing or replacing the motor should rectify this problem.
How to fix a Whirlpool microwave fan not turning off
The general cause of this problem is that the temperature is too high in the microwave, so by addressing this problem we can get the fan to turn off by itself.
In more extreme cases, it may be due to a component failure.
Let’s take a look at the best methods of fixing this problem.
1. Reduce the room ambient temperature
If it’s a hot summer day and you’re cooking a lot of food, the ambient temperature of the kitchen can contribute to heating the microwave.
You can try the following to open the windows/doors to increase airflow in the kitchen, turn your air conditioner on, or run your oven’s fan extractor to help cool the room down.
2. Let the microwave cool off
If you’ve been using the countertop microwave a lot that day, it may have just gotten hot through overuse.
Leave the microwave alone to let it cool down passively, and you may find the fan turns off by itself.
3. Manually turn the fan off
Most modern whirlpool microwave ovens can turn the fan off by hand:
- Head to the ‘options’ menu in the settings (this may also be worded as ‘control setup’ depending on the model of Whirlpool microwave oven you have).
- Enter the setup mode
- Find the ‘vent fan’ function
- Switch it off
Please note that this does not address why it won’t stop spinning, but it can give you a break from the noise while you further diagnose the problem.
4. Dirty control board connectors
Sometimes there can be an electrical miscommunication due to dirty control board connectors.
You can try to remove the control panel and check the ribbon cable connectors. Clean them with some rubbing alcohol to remove any built-up dirt or grime. This may help fix the issue.
5. Disconnect it from the power supply
As microwave ovens lean more into software-based operation, they can easily develop a bug or glitch.
Unplugging the countertop microwave from the mains power supply and leaving it off for a few minutes.
This performs a ‘hard reset’ which can sometimes fix the problem.
6. Clean or replace the filters
If the filters get clogged up, they may need to be removed from the microwave and cleaned.
But if they’re already quite old, it is easier to replace them entirely as once they’re old, they won’t function very well anyway.
7. Repair or replace the fan motor
If the fan motor isn’t communicating correctly with the thermostat, it may have malfunctioned or become defective.
The best option is to replace the fan motor with a new, working one.
8. Check and replace the thermostat
The thermostat is a vital component in operating the fan. It’s what tells it to turn on and off based on the current temperature of the Whirlpool microwave oven.
If the thermostat has gone bad, it will need to be replaced.
9. Clean the grease filter
Similarly to the air filter, it will need to be cleaned if the grease filter is clogged up.
Because grease, fat, and oil are a bit more difficult to clean than the air filter, you will need to use some soap or a good detergent.
If you’re having trouble cleaning the filter because the oil is so stubborn, throw it and replace it with a new one.
10. Inspect the damper assembly
If the damper assembly has been compromised or blocked, you should inspect it visually to see the problem.
If there is some blockage, you can try to unlock it.
But if there is some structural damage, you should replace the entire assembly to help it better direct the flow of air.
11. Contact Whirlpool support
If the above solutions haven’t fixed the problem, it may indicate a deeper, component-level problem that will need a trained expert to diagnose and fix.
You can contact Whirlpool technical support, who will help arrange an expert technician to help you fix the problem.
Adrian is an ISCET licensed professional that has completed the National Appliance Service Technician Certification Exam and has the expertise to diagnose and repair any appliance. He is well-versed in the latest technologies and techniques and is always up-to-date on the latest industry standards.
