Middle Air Vents Move No Air
 

1996 LT4
Why doesn't air come out of my middle air vents and also seems like very little comes out the sides too? Recharged my AC and blows like mad from below and defroster. But nothing from other vents...

Sounds like there is a problem with the actuator door(s) on the HVAC assembly.
Should be lots of posts in here about that kind of thing.

It sounds like the AC programmer to me. The '96's have a vacuum routing block that has rubber connections between the halves. As they age the rubber "nipples" tend to collapse and block the vacuum. When this happens the air blows out of the defroster (top) and heater (bottom) only. There are several comments on repair methods.

My mother's Buick has a very similar system and I repaired it by inserting very small hypodermic needle sections into the rubber nipples to keep them from collapsing and then reassembled the unit. It has worked perfectly for about 15 years now. My total cost was about 25 cents and about a half an hour to do it. The dealer wanted over $500 for the part and over $500 for labor for a total with taxes close to $1200.

Here is a link that talks about the same problem.

https://www.corvetteforum.com/forums...l-problem.html

Good luck.

Thanks. I also read that its possible a hose is pinched when I replaced the radio and reassembled? How likely is that?

You could also have vacuum lines in back of control eaten by mice

It's a 96.. not much doubt in my mind it's at the programmer up under driver side dash. 96 is a one year only on the programmer vacuum hook ups. Mine did the same thing.. i cut the vac lines going into the programmer,,removed programmer, removed the vac hookup from the box.. put 12" of vac line on each color inside the box( labeled them for color ID ), ran lines thru the hole made by removing the vac manifold hookup,,reinstalled programmer and hooked the lines up to each color where i had cut them. has worked perfectly ever since. Can't remember for sure ,,but, i used 7/64 or 3/32 vac line.. It's a pain in the ass to do, but well worth it to have your AC coming out of the fwd vents where it should !!

Isn't floor/def the default mode for loss of vacuum? Check valve at manifold?

Here is an old thread: '96 HVAC Vent Control Problem