Volvo: 93 940 A/C not working, A few questions., 30 amp fuse, 12volts

Question
The AC on my Wifes 1993 940 A/C stopped working. I hooked up my AC gauges to the low side, but haven't found where to hook up the high side gauge. It isn't entirely necessary for me to connect the high side, but I would like to if there is a 'port'. Is there a high pressure AC test port?

Anyway, it was a little low, but I topped it off (a few lbs above ambient temp.). I have no voltage getting to the AC compressor. I had pulled the grill (while looking for the high side port) and saw what seems to be a high pressure cut-out, a low speed condensor fan, and a high speed condensor fan switchs. I also found the low pressure switch right near the low side gauge port.

After jumping 12volts to the compressor, I found that the system works fine. The low pressure switch cuts in around 20lbs and out around 40lbs (from where it 'clicks', I haven't used a multimeter on it yet though). The Condensor fan comes on and off also (I can't remember the pressures). I have checked the 30 amp fuse and it is fine. I have played with the switch on the dash, but haven't pulled it out to check it yet. I did 'jump' the low pressure switch (shorted the connection) just to see if it was a bad switch, but the compressor didn't come on, so I don't think that the low pressure switch is bad.

So, my questions are:
1) Can I hook up my high side gauge? (and where?)
2) Is there a 'common' problem with these cars? (bad switch, or relay)?
3) Does anyone have a Relay panel illustration for this car? Maybe a link?

Thanks in advance for any and all help. I have an idea of what I need to do next, but any direction would be appreciated.

Answer
I'm not sure if it is the same on the 93, but on my 80, I believe the high side hookup is on the rear of the compressor, sort of hidden below and behind the power steering pump.  As for lack of voltage to the compressor, a lot of times the switch in the dash actually breaks, or one of the contacts on the back comes off, I would check that first as the most simple solution.  Another common problem is the failure of the clutch, but it sounds like because you can short the 12V and get the clutch to fire and engage the compressor, that you're OK in that area.  As for a detailed illustration of the relay system, I would recommend picking up either a Hayne's manual or a Bently manual, both have great layouts of everything electrical in the car.  Good luck!