Where do I look? Just put an 84 TD motor in a 92 Jetta (with air) and put the car on the road. The guy that did the safety (at my request, I was short on time) put in a heater core for me. Trouble is, when he got done , he noticed the fan wouldn't run, so found somewhere to jump some power to the switch. So far, so good, right? well, when I got in the car,I figured out the radio doesn't work any more either, and the spot he got the power for the heater was the low beam lights! (Fan quits on high beam). Is there a plug somewhere between the radio/heater and the fuse panel that got knocked loose I need to go looking for? This could turn into an all day job!
Update: Got the radio problem solved. Mechanic missed a plug on the back of the radio, had the speakers plugged in but not the power. Haven't found the problem with the fan switch yet though. (Oh yeah, it's not something obvious like a fuse.)