My 1970 GS has factory air. The selector switch (the one that selects a/c. heat, defrost, etc) is inop. I bought a replacement switch, but it also was inop. I guess the vacuum membrane deteriorates over time and the switch becomes useless. I don't drive the car in the winter, so I don't really need heat or defrost. Is there a way to lock the selection onto a/c somehow and not worry about the switch?
Jon, You have to be a diagnostician, a mechanic, not a parts changer. The entire system works on engine vacuum that is stored in a container on the firewall. The feed for that storage container comes off the back/center of the Quadrajet. First make sure that the storage container is there, and it is connected to the carburetor. There is a thinner line that goes back into the dash through the big grommet in the firewall. If there is a break in any of those smaller lines, and there is no vacuum to the system, air will only flow from the lower heater vents, it will not switch to defroster, or A/C vents. When you flip the switch all the way up to A/C or REC, there is a set of electrical contacts that close and energize the compressor clutch. So depending on the EXACT nature of your problem, you either have a vacuum supply problem, and/or electrical problem. Is the compressor turning?
Thanks for the great info! I tried it again today. The compressor is working and the air coming out is cold. 75% of the air is coming out of the dash vents and 25% on the floor. It freezes your feet. I would like all of the air to come out the dash vents.
