Ok, here is my question. I recently bought an 88 GTA. I took off the little face plate on my stereo and ac/heater box controls. First i noticed that the box didn't really fix in its hole. The screws didn't line up. I was wondering if this was some sort of after market thing. But any ways here is my question. I have the heater box that has all push buttons that click to select your heat, ac, vent, and it has a button on top and one below it and if you hit the one on top that makes the fan speed in crease and the one below makes it decrease. Everything works fine but then when I switch the fan speed to the highest setting it shuts off. It makes no sense. Every other speed works, how come not the fastest.
Thanks
Jason

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1988 Pontiac GTA
Loaded
350 700R4

 

There is a high speed fan relay under the hood near the fan motor. This powers the motor directly when the switch is in the "high" position. Start by checking that circuit out & see if the relay is defective. In the other three switch positions, the motor power comes from the switch & goes through the resistors near the blower motor, in the duct work.


Tim