fan won't turn off

It might be that the System Management Controller (SMC), responsible for controlling the fans, has become confused. You should try the following procedure and see if it help.

SMC reset instructions for a MacBook Air are:

1. Shutdown your MacBook Air (go to the Apple menu and choose “Shut Down…”).
2. Make sure your MacBook Air has external power. Connect the power adaptor, if it isn’t already.
3. Using the Air’s built-in keyboard (not a plug in keyboard or bluetooth keyboard), of the left hand side of the keyboard press Control-Shift-Option and on the top right of the keyboard, the power key at the same time.
4. Release all the keys at the same time.
5. Press the power key to start the computer.

Is there any way to see if the reset of the SMC has worked? I followed this procedure twice now, and the fans are still spinning... I'm just wondering if I'm doing something wrong with resetting the SMC, or if I have another problem.

this help me,

this worked for me. the fan on my air, which i had never even heard before, went on when i had to do a T startup for migration and then would not go off--this fixed it. thanks.

I have a MacBook Pro from 2010 (2.53 GHz Intel Core i5) running 10.6.8. I tried resetting SMC to no avail. Any other suggestions. The fan just started running all of the time a few days ago, even when no user processes are going on. Machine does not feel hot either.

Thanks.