A C blowing cool but can;t control

[wingnut96lt4]

Guys need some help. My A C works fine just that only the defrost position is the only outlet. I push the control buttons for lower legs or dash vent but air only comes up windshield . How do I correct this ???:ugh

 

[ecss]

Assuming this is a 96 with auto climate control.

It could be the vacuum check valve or vacuum hoses under the passenger side fuel rail cover have deteriorated.

For a 96 it's usually the AC Programmer that is mounted on the firewall above the gas pedal more towards the transmission tunnel. The vacuum manifold has soft nipples where all the vacuum hoses attach. This causes the vacuum hoses to collapse so the vacuum actuators don't work.

There are a variety of solutions. None that are easy.

Here's a 3 page link that describes the fix.

http://forums.corvetteforum.com/c4-tech-performance/1514042-96-hvac-vent-control-problem.html