fbi365, I tried to do this first but the pc fan was 12v, so the phone charger wire wasn't a high enough voltage to get a nice speedy fan. It was slow as fuck!  So I bought a variable voltage adapter that you could set anything up to 12v. Annoying to pay for but worked a charm!  

I did the same as the 1st comment. I just screwed the fan into a shoebox which has many holes in it. I leave lid the on and let them dry out 12-24 hours before moving the fruit to the desiccant bowl.

I just used an old cell phone charger, which is 6 or 7 volts, cut off the end, splice the wires to the computer fan, done!  No need to buy an adapter...