AC Compresser question

First of all I want to thank everyone who's been most helpful in answering my questions! I'm learning and it has been a tremendous help!

Here's my lastest dilemma..I cannot get my AC Compressor to kick on via Control switch on console. The switch looks like it has only vacuum lines coming from it. Inclosed is a picture of the wiring coming from compressor. The compressor has 3 wires..! Black (Ground) and two Green. One of the Green wires runs to the "Low pressure switch" which when followed its disconnected.(Why I don't know and were it goes I also don't know,) I was thinking it was for a fast idle switch which this carb does not have. I cannot find the other end to connect it to. The other Green wire goes into the wiring harness by the fan relay. I don't know were it goes from there. I'm thinking into the harness thru the firewall. Not sure though. I have no power to Low pressure switch at all. Howeve, If I connect that wire thats disconnected to a live source and move the AC control switch to AC High or low it will kick on the compresser and blow cool air thru floor vents. But I cannot get the switch to adjust the air to upper vent or defrost. Looks like I have mutiple problems? Is there a hot wire and were might I find it at tye control switch..Like I said I only see tiny vacumm lines coming from it. Any help would be gratefully appreciated! Also I haven't tore the dash apart yet

I think you're going to have to get a Factory Service Manual that has the wiring diagram in it. Or you can get just the wiring diagram from some of the aftermarket Corvette suppliers.

Do you know what kind of freon it has in the system? You will need to know that in order to determine if it has the proper charge in it.

hope these help

this is for 77 

Thank you! Thank you! Thank you!

That helps tremendously!