On my camaro my fan for the AC and the Heater works on all the setting except Hi. I figure there's a bad vacuum line some where. Any ideas of finding the problem.

 

I think HIGH is controlled by the relay - it should be attached on or near the heater box under the hood. The resistor that is attached in the heater box controls the lower speeds. Vacuum leaks tend to make the air blow only out the defrost vents, and don't have anything to do with the speed of the fan motor.

 

Loss of high speed fan function can be caused by a blown fuse link. Does your underhood light work? If not, check for power at the inline fuse to the underhood light. If no power, look for fuse link B to be broken.

 

Well i got my fan working I had power to all the RED and the Orange wire so it had me stumped. The relay was replaced before and the person before me just wrapped wires and electric taped them so that was like a WOW. Some of them were corroded so I cut them back and soldered them and now it works. Now I did something when I took my interior out and only the defroster works so back to trying to figure out whats wrong

 

If only blowing at defroster vents, that's a vacuum issue - might have a vacuum line on the back of the heater controls come loose or sprung a leak.