I am just new to this forum and I'm looking for advice on a heating/ air condioner problem with my 80 Vette.

Welcome to C3VR, first!!

Definitely sounds like a vacuum problem. You may not be getting any vac. to the selector at all, or the selector may be dried out, unplugged, or otherwise damaged.
Try taking the selector/switch assembly out, and looking to see if the vacuum plug is connected, first. This will be a plug with several flexible, colored vacuum hoses on it. If it is not plugged in, then that is most likely the problem. If it is plugged in, unplug it, and start the car. You should be able to feel vacuum on at least one of the hose ends. You may need to use a vac. gauge, but usually, you can feel it. If there is vacuum, then the selector switch has probably dried out inside, and needs to be replaced, or some of the hoses that go to the vac. servos are off.
If there is no vac. at any of the ends, then you will need to start looking under the hood for a small vac. line that is not connected.
This should give you something to start with, anyway...good luck!! See what you find, and let us know.

Joel,

Ian, you may need to replace the vacuum canister on the main air box. I had mine apart a few years ago and can't really remember. But the canister shifts the air flow by swigging a large flap inside the air box. And sorry to say its a B*$%ch to get to. Also check the heater/control located in your console. Thanks

The vac. servo by the pass side kick panel is for the "Max A/C" door. It should be open in any position except "Max".

I'm not familiar enough with the guts of an '80 dash, but I would suspect you will need to at least remove the glove box, to get look back in there. The earlier cars, you can remove the pass side dash panel, and get a decent look, even tho you may not be able to get your hands on the parts!
It does sound like one of the doors is stuck, or has a bad servo, as Guy says...

joel, i need to ask a question.  my a/c doesn't work in my 78.  i would like

Depends on how far you want to go with it! If you just want to remove the compressor, condenser, and the lines, then that's all you need to do. This will not effect the operation of the heat/defrog.

If you want to totally remove all aspects of the A/C system, then you're talking about a major undertaking, involving replacing the heater core/plenum, console controls, and vent outlets, with non-A/C car parts. Lot of trouble, imo...

  oh no,  i just wanted to take the stuff out from under the hood, not everything else.   how do i go about knowing which stuff to take out, undo, etc

Just start rippin crap out!!

You can remove the compressor, and the brackets(at least some of them). The hard and rubber lines from the comp. to the condenser. The condenser itself(in front of the rad). Plug the hoses/lines that are left on the car(going inside the cabin), and yer done!


btw...we may need to take this to a new thread, so this one stays focused on the original topic. Adams' Apple2007-10-12 20:11:24

thanks.  sorry for buttin' in on the wrong forum