People sweat, dogs hunt and laptops turn fans generally to stay cool. Unless you have the small, fanless MacBook ($ 1,249 at Amazon Marketplace) then your MacBook Pro ($ 1,789 at Amazon.com) or MacBook Air ($ 793 at Amazon Marketplace) will occasionally heat up its cooling fan to keep its thermals at bay. If your Mac's fan has turned from occasional spinning to regular and loud spinning, here you can slow down the roll (or even the spin).
Reviewing apps and tabs
The more apps and browser tabs are on your computer, the more likely your Mac will have to use its fan to keep things cool. Minimize your multitasking by closing applications when you stop using them, especially if you use graphics-intensive applications like Photoshop and iMovie.
To see which apps use the most CPU resources, open the Activity Monitor and click the CPU tab. In my experience, Chrome is more a resource than Safari, so you could try switching browsers for quieter web browsing (and good news, Safari gets favicons!) I also use my iPhone ($ 1
Keep Vents Clear
The MacBook Pro has vents on the sides and rear, and the MacBook Air has vents on its trailing edge. These openings suck in cool air and displace hot air. If you block these vents by resting your laptop on a lap, sofa cushion, pillow, bed, or blanket, your Mac will heat up quickly. I use a coffee table book to keep the vents on my MacBook Pro unhampered when I'm lying on a couch or in bed.
If it looks like a pile of dirt has accumulated on the louvers, you can try to blow it away with a can of compressed air. Of course, you run the risk of simply blowing the debris into the Mac. If that seems to be the case, then you need to open your Mac to get under the hood.
Open and Clean
Get a tiny phillips head screwdriver and you can remove the bottom plate of your MacBook to remove dirt, dust and grime that has accumulated over the years. Use your compressed air can to wipe off dirt or a lint-free cloth to wipe it away. Pay special attention to the fan and its fans, as well as the entire back of your MacBook. The goal here is clean passages for maximum airflow.
Test Your Fans
There's a possibility that the reason for overheating your MacBook is that something's wrong with the fan itself. Your Mac has a hardware diagnostic tool burned in it. If it was created before June 2013, use the Apple Hardware Test. After this date, use Apple Diagnostics.
These tools work in a similar way. If your MacBook is plugged in and all external peripherals are removed, restart it and hold down the D key to start one of the two diagnostic utilities.
Follow the instructions on the screen to start the test. The standard test takes only a minute or two and will report all hardware issues. For a more thorough examination, you can check one box to perform an extended test that will take an hour or more.
View this Apple Support page with reference codes that appear in the Test Results section when the test is complete. There are three codes, all of which start with "PPF" relative to the fan. If you get any of the results that indicate you have a problem with your cooling fan, contact Apple Support or visit your nearest Genius Bar.
If your Mac is clean and free of dirt, it's free and you keep your apps and tabs in check and the fan is still spinning around a lot, then you try to reset the System Management Controller (SMC). The SMC is responsible for controlling low-level features on your Mac, including "Thermal Management", also known as a fan. Follow Apple's instructions to reset the SMC.
More information: Everything you need to know about MacOS Mojave.