For some reason when I turn on my heat, air conditioning and vent, nothing comes out of the vents, but it comes out of my defrost vents. I dont know what the hell happened but ever since i had my stereo installed it hasnt worked right since help!.

 

I'm guessing but it sounds like you may have disconnected one of the vacuum hose that drive the vent operation. Did you see any of these hoses when you had the stereo out?

 

Definately sounds like a line was knocked off.

Did the same thing in my car after installing the deck, Who woulda thought getting 12 strands of 8ga wire, 2 RCA cables and the antenna wire in there would be such a big deal

 

went back to shop they saw nothing, not real good when it comes to fixing things on cars.

 

The vacuum line may have gotten kinked. If it broke or got loose, you would probably have a hissing sound coming from the radio pod and the car may idle funny.

I broke the line that goes into the car from the engine bay so I am also stuck with only defrost vents.

 

Now that you mention it, My car does idle a little odd, and I dont seem to hear any hissing sound from the radio, but it could be that I am def jk.

 

You lost vacuum to the heater controls. It's a safety feature built in. If controls are lost it defaults to defroster. So you can always keep windshield clear.

 

Thats happening to my car, i didnt do anything, it just stopped one day.

 

Hmm thats something that I didnt know, but I do now so

 

my car does this too. how do i fix it? its going to be gettign cold here soon and i want heat on me.

 

Most often it's a bad vacuum line going to the control unit. In my case the unit was shot ( lost it's seal) and I replaced the whole thing. Listen for the hiss sound of escaping vacuum and work from there.

 

how much did it cost to replace the unit?

 

I dont remember what I paid. You could get a used one from Hawks or new from year one or GM.

 

My car started doing that right after i had the radio out to run the cables to my amp. I also ran the hot from the battery, all the way through the car.
I guess on my way back to the firewall and into the car, I must have leaned on the plastic (?) vacuum line (that runs down and into the firewall) and broken it.
It was the one coming from the heater control valve. So when I removed the control valve I just capped it off.
Not sure if any of your problems are the same, but if you had something done under the hood, check around there too

 

Since the HSR swap, I've had the same problem, so I am pretty sure it is my vacuum line (or lack thereof). Anybody got pictures of what it should look like since I can't remember much of what came with the TPI and what I got rid of.

 

TGO Guys,

Last weekend I spent a great deal of time troubleshooting a similar problem with my son's Z-28 (Defrost Only).

I followed all the lines and they were fine.
Intake Vacuum to Canister Near Wipers - OK
Canister to Connection Near A/C - OK
Vacuum Present on Control Assy. - OK

A very close look at the valve assy. found that the "TIT" that connects the valve to the lever assy was broken off. I purchased two complete control spares + an extra valve assy. from the U-Pull-It yard for only $5!!!! I did find that the first two J.Yard cars also had the "TIT" broken off. That's why I decided to get a couple as this MAY BE a common or recurring problem.

Problem Solved (for my son anyway)!

Sincerely,
Kurt