My macbook air is very loud!
Plug in your power adapter and turn the machine off. Press and hold control+option+shift+power buttons for 5 seconds. This resets the System Management controller, which is in charge of power flow through your machine and also things like the speed of your fan.

http://support.apple.com/en-us/HT3964

If that does not help, the computer may still be damaged. Where did you have it repaired?