71VETTE

I am having problems with getting my fan to go into high speed on a 78 Vette. I replaced it but when I put it on th highest postion it does not blow at all. The fan turns on in the first three positions but when placed in the 4th it shuts down. Any suggestions?

Al :)

mrvette

Yes, due to the high current requirements of the blower motor in high speed, GM routed the high speed power through a dedicated relay located on the evaporator box, right above the headers, where it gets baked out pretty good, OR the hi speed blower fuse, is located near the driver's fender linder near the horn relay/power take off point...typically in a white fuse clip....
corrosion may be making the fuse get hot by now, and so needs cleaned up at a minimum, better off replacing it really....I used a spade lug modern holder and fuse...with weather cap....the relay wiring/plug maybe also corroded, make sure the relay actually closes, later sharks may have a bad controll console also....but doubtful in probability....

GENE

page62

I had a corroded connector on the relay hi-speed fan wire. Easy fix. Get a genuine GM Shop Manual for your car if you can. It covers the electrical system fairly well.

Wrencher

Like they said. Mine had a hi-blower relay burn up, then a bad connection at the relay plug a week later. Works great now. Funny, the relay for a '69 vette was $48.- and the EXACT same relay for a '69 chevelle was only $30.-! :mad

Hans