I have a non climate controlled c4. With the ac/heat in the off position I get outside air blowing out from the under dash vents. Also myblower motor switch is not working all of the time. Any help would be greatly appreciated.

 

Is the air coming in all the time or just running down the road? What year is your car?

 

Just when running down the road. Car is 84.

 

If you have a Max or recirulation button, then drive while this button is selected if you don't want outside air coming in. The direct air which the button looks like an arrow going straight through the car is if you want outside air to flow. I hope this is not too confusing. It is best to drive around with the max or recirculation button selected so you don't get outside pollution and fumes from other vehicles. Just crack your windows every now and then to get some fresh air when not behind other vehicles. BK

 

Early model GM's ran the blower on low even if the switch was turned off for fresh air ventilation. I know the trucks did and I think the 84 does to.

 

I dont see any fresh air button on these controls. All I have is a dial for fan speed and two sliders . The upper for heat/ac/vent , the lower for temp control. Any suggestions?

 

Could you send a pic to me? BK

 

When you turn the key on with the controls off, do you hear blower motor on low speed?

 

With controls off, blower motor does not turn. Is there a external air valve for inducting fresh air. Its my guess that its stuck open, or the whole temperature switch array is bad?

 

My guess is the mode switch cable is either broken or out of adjustment. The controls on your a/c is all mechanical and vacuum controlled. Blower switch being intermittant, I would say bad connection at the blower motor (power and ground), or at the the blower resistor or switch.