I'm trying to figure out why my A/C won't turn on.
IT's a '91 turbo wagon. Still running R12. 1) compressor
runs when directly powered.

2) pressure cutoff switch at receiver/dryer passes current,
so I assume I have adequate gas pressure.

3) I don't get current at that switch, and the front
pusher fan doesn't get power.

4) Wondering if the a/c button on the dash wasn't working,
I switched out the control unit with one that was working.

5) What next? Is there another pressure valve that I don't
know about? Where is the relay that the button on the
temp control activates? I had to replace the heater core
over the winter, maybe I loosened a connection, but
I don't know the wiring routes.

Thanks for any help!