You might think your MacBook is overheating if it sounds like a hairdryer and feels like a grill. When your computer gets so hot that it randomly turns off, you’ve definitely got a heat problem. There are a few things to remember when troubleshooting an overheating laptop, and today we’ll pay special attention to the relatively silent MacBook Air.
For the purpose of this article, I’m going to define “overheating” as being very hot to touch but still operational.
Know Your Limitations
An overheating laptop can be caused by all sorts of things, from dust buildup to failing fans. Sometimes it’s easy to overlook the more obvious signs, like simply using your laptop to its full capacity.
The MacBook Air is a very compact machine and that means heat dispersal isn’t a strong point. This particular Mac only has one vent, and it’s located on the hinge. That means your laptop is very likely going to cook under load.
Intensive processes like rendering video, playing games, or leaving fifty tabs open take their toll on your processor, which generates heat that only has one route of escape. These machines were simply not built for demanding tasks and that’s reflected in the cooling supplied by Apple.
You can help this problem by ensuring you don’t block the fans. Using your laptop on your lap, in soft furnishings, or in bed will reduce its ability to cool itself, so a nice sturdy desk is a better place for extended periods of use.
If you’re going to plug your MacBook Air into an external monitor, make sure you provide plenty of room for ventilation — driving an additional screen puts strain on the GPU, generating yet more heat.
Drop The Demanding Software
Have you ever walked into the room to find your laptop loudly cooking itself for no particular reason? You can find out exactly what process is causing your MacBook Air to work overtime by launching Activity Monitor (search using Spotlight or find it in Applications > Utilities) selecting the CPU tab and then clicking the CPU column to sort by descending order.
Processes will be ranked by the percentage of available processing power they are consuming. Anything that’s using excessive amounts of CPU (think 90% and above) for no particular reason has probably crashed and can be killed by clicking the process and then forcing it to quit with the X button.
The MacBook Air in my household (still running OS X Lion) would encounter repeated crashes in Google Chrome even when not in use, causing the fans to spin up at random intervals. Dropping Chrome and going back to Safari completely solved this issue, but so does limiting the number of tabs you leave open — in particular Gmail and Facebook.
Disabling web plugins by default will also stop demanding Flash videos and adverts loading automatically, which has the added benefits of speeding up your web browsing experience and saving battery power too.
Limiting background processes may also help, so stopping any unnecessary programs starting up under Settings > Users & Groups > Login Items will help save your RAM too.
Test Your Fans
If your problems are a little more pronounced and your MacBook Air is regularly cutting out, you may need to test your fans. Not long ago, I encountered a MacBook Air that had developed a problem with the fan after only three years of use, which was obvious due to a grinding noise — but not all fan failures are this obvious.
Fortunately, you can test your machine using Apple’s online hardware testing facilities. If your MacBook Air was made prior to June 2013 you’ll use the Apple Hardware Test, and if it is more recent it will use Apple Diagnostics. Don’t worry though, they’re very similar and are accessed using the same method:
- Shut down your Mac and connect the power cable.
- Press the power button and then (before the gray startup screen appears) hold the D key.
- Select a language if prompted, then follow on-screen instructions.
If you’re using Apple Diagnostics on a recent Mac (screenshot, below), you won’t need to do anything as the test will complete automatically. You should make a note of any error codes or other pertinent information, particularly if your machine is out of warranty and you will need to conduct repairs yourself.
If you’re using Apple Hardware Test on an older Mac, you will be prompted to either perform a basic test or a thorough test. The basic test should be enough to detect cooling problems.
Machines that shipped with Lion (OS X 10.7) or later will be able to send this information over the Internet to Apple, handy if you want to make a Genius Bar appointment (particularly if it’s under warranty).
Override Your Fans
If your MacBook Air is consistently cooking and you’re struggling to see why you may want to install an app that allows you to manually override your fan speed. smcFanControl is a free program that lives in your menu bar and provides a quick readout of your current CPU temperature and fan speed — though modern the program doesn’t work as well with modern Macs.
The app allows you to override Apple’s own rules about cooling your MacBook Air by increasing the minimum fan speed, with the ultimate aim of prolonging the life of your hardware.
Your MacBook Air will always shut down when the temperature gets too high (somewhere around 105ºC), but operating hardware at temperatures near this shut-off point may also be damaging over time. By forcing the fans to work overtime, you will have a louder laptop that cools faster but also places more strain on the fans.
Hardware Life
Some users believe this results in prolonged hardware life, even if it means they have to replace the fans sooner than they would like (a fan will cost you around $15, and a logic board is closer to $600). The app allows you to create profiles under which you can specify minimum fan speeds, with rules for automatically switching profiles depending on your power source (remember: a plugged-in MacBook Air is a hotter MacBook Air).
If you find that smcFanControl doesn’t show what your Mac is currently doing (either the temperature doesn’t display or the fan speed reads “0 rpm”) then you can install iStat Menus ($16) which provides lots of information about your machine, including fan speed and temperature. This program does not allow you to control your fans, you’ll still need smcFanControl for that.
Finally: Laptop Coolers & Cleaning
It’s a last resort, particularly for such a mobile laptop, but sometimes you have to bite the bullet and buy a cooler. This is an ideal solution if you’re using your MacBook Air as a primary machine, with a second monitor and keyboard setup that your cooler can slot right into.
If your Mac is older and you’re noticing the fans spinning up a lot more than they used to, you may want to go a step further and clean it. This involves opening up your laptop and exposing its delicate inner workings so, while you’re unlikely to break anything, you really should take care if you decide to do this.
iFixit covered the MacBook Air range, with complete instructions for opening them up and putting them back together again. If you are going to go ahead and clean your laptop, make sure you buy a high-quality computer duster (canned air) with which to do it.
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