Noise coming from direction of belts... please help

I have a hissing noise coming from the direction of the belts / fan at the front of the engine on my 95 Sidekick 16 valve. It's very similar to the noise you would hear from a leaky air compressor hose. At first, I thought I should check to make sure all the pulleys were turning and that the belt was not being spun around one that had seized up. So, as always, my first impression was not correct. Now, I'm stumped about the situation. What could be making the noise? I have checked to make sure nothing is rubbing or touching the belt and also the fan. I don't know what it could be. If anyone else has had this problem please let me know if and how you got it fixed. I need it in good condition to drive back home for Thanksgiving. Thanks!!!