Why Does My MacBook Fan Keep Running?

Your MacBook fan has one job: to keep your system cool enough that it doesn’t overheat. When you hear your fan running, you know it is trying to cool down the internal components, but what if it runs all the time? Does it mean there is a problem?

It doesn’t necessarily mean there is a problem, but it does mean your MacBook is working hard or is not getting good ventilation. If there is a problem causing one of these two situations, there is usually a simple solution, but it is most likely not a problem with the fan itself.

My name is Eric, and as a longtime engineer, I am always curious about how things work and how they are designed. Your MacBook’s fan is there to help keep it cool, so if it keeps running, there must be something causing its temperature to be elevated. 

I have found 5 good reasons for why it may be running hot and how you can fix most of the things that may be causing this condition. Keep reading below if you would like to find out more.

What You Need to Know about MacBook Fans

Before we discuss why your fan is running and what you can do about it, I will first give some general background information about MacBook fans. With the many different versions of the MacBook over the years, there are also many configurations for fans.

Some MacBooks have multiple fans, others have only one, and some even have no fans. Obviously, if you have a MacBook with no fans, you should not hear any fan running; otherwise, you have real issues, but for others, hearing the fan run is not uncommon.

Actually, the fans run all the time. It’s just that you may not always hear them. They run constantly to keep your system cool, and at normal temperatures, they run at a lower or idle speed which you may not hear. 

When things heat up, the fans increase their speed to keep your system cool. So when you hear them, they are just doing their job, but if you hear them constantly, it means they are running at a high speed continuously, which means your system is having trouble cooling down, possibly indicating a problem.

In the next sections, I will discuss the main reasons you may be hearing your fans run constantly, and we will take a look at some things you can do to keep your system cool and keep the fans a little less noisy.

1. Poor Ventilation

The sleek design of your MacBook looks cool, but its design is not just for looks. It’s also designed with ventilation in mind. The location of the air vents and fan is designed to create good circulation throughout the interior of your machine. 

Even the body of your computer is designed to dissipate heat effectively, but the fan, air vents, and body cannot do this in certain situations. If the air vents are clogged with dust, it will reduce airflow. If you set your laptop on a soft surface such as a couch or bed, it will also not dissipate the heat.

If you work outside in the heat or don’t have air conditioning on a hot day, it can also be hard for your system to cool down. Any of these conditions can lead to your fan working harder and running at higher, more audible speeds for extended periods.

The solution here is to do things that help keep your system cool. The following are suggestions that can help. 

Keep it Clean

First of all, you’ll want to keep your system clean. Make sure the vents are not clogged with dust and debris. Cleaning the computer’s exterior is also important because MacBooks use their aluminum body to dissipate heat. 

Dirt and grime built on the surface can keep it from cooling. It’s probably a good idea to clean your computer at least once a month to prevent the build-up of dust and dirt.

Natural is Cooler

Adding stickers, skins, shells, or protective cases to your MacBook is fun and looks cool. It’s great to personalize your machine, but this can affect the temperature of your system. If you add materials with insulating properties to the outside, it will hold the heat in.

Try removing external materials, especially protective cases, and see if that makes a difference. It can be disappointing not to be able to use these things on your MacBook, but the MacBook already has a nice, sleek look, and preventing overheating should be a higher priority.

Location, Location, Location

It’s said to be the most important thing in real estate, and it’s also pretty high up there when it comes to the placement of your MacBook and its ventilation. I know MacBooks are meant to be mobile. It’s one of their great features, but remember where you place it.

Keep the area around it on your desk clean and clear of cords, books, paper, debris, and other items that can restrict airflow. Also, when possible, set your laptop on a hard surface. Putting it on the couch, a bed, or a blanket will restrict airflow and cause overheating.

It’s also wise to keep it away from heaters or other electronics that put out a lot of heat since they will only raise the temp of your machine and cause the fans to run at higher speeds. Work in a cool, temperature-controlled room with good airflow.

Props for Better Airflow

Sometimes, the location where we need to use our MacBook is unavoidable, and sometimes, even setting the system on a hard surface does not provide enough airflow to keep it cool. In this case, you may need to use something to prop the laptop up slightly to provide better airflow underneath it.

Often, it only takes a small gap to get just enough to keep it cool. I will sometimes place a pencil under the backend of my older system, which has this problem, but there are also computer stands that you can purchase that will elevate your system to provide better airflow around it.

Need a little Help

It may be time to provide external cooling help if all else fails. A small external fan near your laptop will help keep it cool. I have done this before when I work without air conditioning. 

Small desk fans work great, and there are also fans made specifically for this that plug into your USB port so you can take them anywhere.

2. Too Much Processing

MacBooks are built to multi-task, and for the most part, they can handle processing many things at one time, but there are limits, and like any other computer, a MacBook can only handle so much. 

In fact, too much processing or even one application that weighs very heavily on the CPU or the GPU can significantly increase the temperature of those chips. This will, in turn, cause your fans to run at higher, more audible speeds.

You can check what applications are running on your Mac and how much processing power they use with Activity Monitor. To start Activity Monitor, click on Spotlight Search in the upper right corner of your screen and type Activity Monitor in the search field.

In the results, click on Activity Monitor to start the utility. Once started, you will see statistics for all applications that are running. You can click on the columns to see which applications use the highest CPU and GPU percentage. 

If an application uses a very high percentage of CPU or GPU, it can cause the chips to run hotter, and the fan will run at a higher speed. You can quit the application by double-clicking on it and then clicking on the Quit button for that application.

If your fans get quieter after quitting the application, you will know it is that application causing the problem. 

3. External Devices

If you have external devices connected to your MacBook, such as a monitor or disk drive, they could be causing an increase in temperature. Try disconnecting each external device, one at a time, and wait a few minutes or so to see if the fans reduce speed.

If they do, it may be that device causing the issue, and you will need to be aware that when you are using it, your MacBook will run at a significantly higher temperature. Therefore, the fans will run faster and be much louder.

4. System Controller

Your System Management Controller or SMC controls the hardware in your MacBook, and the fan or fans are one of the things it takes care of. The data in your SMC and the data in your NVRAM/PRAM affect how the fans run, and this data can sometimes get corrupted.

Resetting both the SMC and NVRAM/PRAM can often cure a problem like your fan running at high speeds. If you have a newer MacBook with an M series chip, just shut your system all the way down and then start it back up, and this should reset both of them.

For older MacBooks with Intel processors, you must follow Apple’s recommended procedure for resetting SMC or NVRAM/PRAM.

5. Fan Problems

If none of the suggestions above helped to quiet down your fans, then the fans need to be cleaned on the inside of your MacBook, or they could be worn out. This can happen after extensive use of any system and is very common in older machines.

You will most likely need a professional to clean or replace loud fans in your MacBook since the computer must be opened up. 


Your MacBook may be configured with one or more fans. If so, the fans actually run all the time to keep your system cool. At times, when it begins to overheat, the fans will speed up, and that is when you hear them running. 

If you hear them running constantly, it usually means your system is at a higher-than-normal temperature, and you may need to take some action, as described above, to help cool your system down. I hope the information provided above can help you to do this.

As usual, let me know if you have any questions or comments. I would love to hear from you.

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