I’ve noticed that, after upgrading from Mountain Lion to Mavericks on my borrowed MBA, my fan was running a lot… and loudly. As in, moving my mouse caused the fan to run at full speed.
I tried rebooting (and unchecking “reopen apps at startup”), which helped for about 5 minutes.
I tried closing down apps (which helped; especially keeping Mail closed helped a lot). But even watching a YouTube or playing Music on Google Music caused the CPU fan to start spinning way louder than before.
It quickly came to a point it started driving my crazy and I had a really loud machine which was also sluggish and laggy at some random points (=> not sure if it’s related, but I haven’t had it since).
The thing I tried was a SMC reset, and that did the trick. Since then I haven’t heard the fan on normal load anymore.
Do this (on an Air):
- Turn off the Mac
- Be sure it’s connected to the Magsafe
- Hit left shift + ctrl + alt (option) + power (like just one second or something apparently)
- release the keys
- and boot normally (hit power button)
- that should be it
More info on a SMC reset is here.