Be sure its coming from the fan, noises typically bounce around and are hard to pinpoint. The weight of the fan usually takes out the water pump bearing. It could also be the idler pulley. Pull the belt off and turn everything and listen/feel for a bad bearing.
i had an idle pulley go bad on my dakota after about a year. plus if you get one and thats not it you can always clean it up and take it back!!! but you might wanna try a new belt cause when they get old they can make some noise too.
i had a pulley go bad on mine, the one on the belt for the a/c. it eventually locked up and the belt kept sliding acrossed it and then snapped. but it wasn't very impoertant cuz it was only for a/c and now thats it's winter i am not too concerned