Not having a wiring diagram in front of me- I'm going to guess that you didn't check the ac fuse in back of the fusebox. There is an inline fuse holder on the wiring side(back) of the fusebox. It is best to pull the fbox down not only to see the fholder but also to check the connection. 82 thru 84 spiders might have this connection butt connected with a plastic 2 to 1 wire scotchlock. There might not be enough amps running through these connections to operate the ac system. If the wire has a in line fuse that uses a ceramic or glass fuse it should be replaced with a blade or GM style fholder. If the wire is connected using a plastic butt connecter it should be soldered.