"If you unplug the low pressure wires and bridge them the clutch should engage. Do this with the engine running and the AC on."
I think the pressure is okay because there is continuity across the low pressure switch terminals. But there is no current to the switch, so the clutch doesn't engage. That's why I think it may be a relay in the system. All of the fuses are okay.
1986 560SEC: 150,000 miles, runs great, but I've got to sell it (too many cars for one man)
1987 560SL: 122,000 miles, used to run poorly, now (thanks to forum), runs great!
1997 GMC Jimmy: Turned out to be a turkey.
1989 T-Bird Super Coupe: 150,000 miles, still runs great. Ford got it right.