MacBook fans are running high even under normal load
Solution 1:
You should first determine if your computer is actually working harder due to some process(es) using a lot of CPU when they historically have not. Open the Activity Monitor app and check your CPU idle percentage.
If your system is using a lot of CPU, the higher fan speed is likely justified.
If you are consistently showing >90% idle, while your fans are racing, you likely have a 'mechanical' heat issue (such as dust/grime on heat sinks or some air blockage.)
If it IS a dust issue, I'd expect you would have noticed the fan gradually increasing its 'unloaded system' speed over time.
There are also products that will let you monitor various sensors in your computer. Some will also let you control your minimum fan speed. My favorite is iStat Menus which has lots of options for what you want to watch and how you want to see it.
Solution 2:
An SMC reboot will do the trick. I had the same problem after upgrading to Mavericks with my 2012 MBA.....here is a link to how to do it.
Solution 3:
So I have been having this problem for the last couple of weeks . I finally fixed the problem and it was so weird I just had to post how I did it for you guys.
I tried all the regular things every forum tells you to do such as: Reset SMC, Reset PRAM, Ran Diagnostics, Cleaned the fans and heat sinks, Changed power cords ... nothing worked.
- I downloaded iStat Menus
- I saw that CPU PECI Die was running at 300 degrees
- Then I noticed my CPU usage bar would just to 101% and every time that happened a process called CUPSD was activating. So I googled CUPSD and found out that its a wireless printing protocol.
- So I went into System Preferences / Printers and deleted all the printers I added the printer I use regularly again And VOILA, The temp on the PECI die went down to 91 degrees and the process stopped happening.
Weird but it worked! Had to share.