My MacBook air has a fan that won't stop yet the system won't restart

So did you get the mac to restart? If not, hold the power button down for longer then 5 seconds and see what happens.

try an SMC reset:

1. Shut down the computer.
2. Plug in the MagSafe power adapter to a power source, connecting it to the Mac if its not already connected.
3. On the built-in keyboard, press the (left side) Shift-Control-Option keys and the power button at the same time.
4. Release all the keys and the power button at the same time.
5. Press the power button to turn on the computer.
   Note: The LED on the MagSafe power adapter may change states or temporarily turn off when you reset the SMC.

SMC worked for me!

SMC Worked for me too!

Unfortunately the fan constantly on issue occurred again a few months later, and no SMC or any other software-based solution worked. Turns out the motherboard needed to be replaced, fortunately my MacBook Air was still under warranty.

Worked for me too. Awesome thanks man.

Thank you!!!!

This SMC reset thing worked for me too. My MBA is a lot quieter now.

I've noticed that my battery doesn't last very long. Hopefully it solved my battery problem as well.

Worked perfectly!! Thanks!