I just purchased a 1978 F150 and the ventilations system does not work properly.

The switch that controls the air flow to different areas (hi-lo, vents, etc...) does not work in that the air never moves from coming out of the defrost vents no matter where the switch is moved to.

What would cause this? bad switch? no vacumn? vacumn motors not working?


I have checked a lot of the vacumn lines and the rubber appears to be good.

How does the motor create the vacumn in order for the system to work? Could this system, whatever it is, be the culprit?

I've also noticed in Chilton's there are two motors in the lines, one for heat and I think the other is for defrost?

The truck is very sound and in good shape, but needs attention w/ weatherstripping, and other seals.

 

I would try posting this in the pre1997 forum found a little further down the page. There isn't much discussion of this site about trucks of that age here. (At least that I've seen anyways.) Try a couple of the other popular ford sites:

http://www.ford-trucks.com/
http://www.flatratetech.com/

and there are many others if do a search with Google.

 

i think you may have pull switches right ? if so there is a wire or a cord that works that and it may just be broken.

 

I pulled the switch system out of the dashboard and move the lower switch back and forth. I saw movement by a small white plastic "wheel?" but again, I didn't really check for a wire.

I will do this.

thanks,

Also will post in the pre 1997....just started coming to this website and didn't notice it the other day.