glad ya got it worked out, just curious though why you used a potentiometer for the fan? i could see you using it if you wanted to control the fan speed, but other then that i dont know...did you like mount it inside your cabin so you could start/stop the fan manually?

if you want something that will be easier on you and not run your fan the entire time, search "Fan Switch" on Summitracing.com. they are pretty cheap, 25-50 dollars for a decent setup and setup within an hour or so for an electrically inclined person. or you could also wire a relay inline with the fan, and pull the 12V signal from something that is hot when the key is on, but itll still run the fan all the time while you drive. just some suggestions though.