80's AC VENTS, Only blowing out the bottom.

[Ken's67]

This is on a '80 Corvette. The vent control are not working. The fan only blows out the bottom ducts. (Feet area) I switch to the "vents" or "defroster", and it still just blows out the bottom ducts. What I'm I looking for? Is the problem in the vacuum diaphrams, or vacuum lines? Is there a easy way to test this system?
Thanks Ken
Sorry about an 80's question.

 

[67HEAVEN]

I'd be willing to bet you'll get an easier answer in C3 than C2.

 

[crause]

Ken,

I can only hope your problem will be as easy to solve as mine was on my 75. I was having the same problem and come to find out the problem was that I did not have the vents open. If yours is the same as mine, there is a pull type knob just below each of the side vents. I thought these were for the fresh air vents but they control a butterfly inside the vent. If they are not open then the air will be forced down to the vents by your feet. The vent on the top of the center guage cluster also has a contorl knob/lever. You have to kind of look under the lip by the vent and there is a lever that moves front to back to open this vent. I hope this is the problem because if the air is coming out of the heater core box (dont know the real name) then the proper doors are openning.
Hope this helps.
Andy

 

[titan81]

If thats not it
check under the bezel right by the drivetrain under the carpet
There is a vacuum plug. It has 4 or 5 lines, I bumped mine out with out
realizing and had no air coming in at all.