my 87 TA has the push-button semi digital air conditioning. The air is cold but the fan seems weak. I have checked and of the 4 settings only 2 work. speeds 1 and 2 are dead. 3 shows a little airflow and 4 is what I would expect 2 to be. Does anyone have a wiring diagram so I can try jumping out the wires at the AC head and the relay.... to try to narrow this down? I suspect this system works kind of like a 3 way light bulb but I can not quite figure it out? Is it voltage modulated or are there multiple sets of coils that are triggered to increase fan speed.



Thanks
-todd

 

I spoke to the guy at the auto Parts store and I was told that the resistor controls the speed. Is this correct? Anyone know how? is it increased voltage?

 

There's a "resistor" thing in the blower box, under the hood. Its got three or four resistors in it, that control the different fan speeds. They're probably not what you'd expect a resistor to look like though, they're just different size wire coils. I haven't had to change one yet, I'm not sure exactly where on the box it's located, but pretty much all GM cars have it there somewhere. Looks like this (the wire coils will be hidden from view, inside the box):

 

The resistors control the speed of the fan for the first three, lower speeds. At high the power goes straight to the fan, no resistor. If your fan is running low at all speeds, it's likely the fan motor not the controller. A replacement fan is like $15-16 at AZ. Try jumping a hot wire directly to the fan. If it runs the same, slow speed as the 'high' position you'll know it's the fan.

 

Thanks guys ... I have owned mostly Ford and one Plymouth. I amazed at how different the GM is. I definitely have an uphill learning curve but I love the fact that GM re-uses parts from stock. Ford changes everything constantly making it a nightmare to comb the boneyard for parts.