2007 XC 90 V8 AC not working

[JRCDave]

My wife has a 2007 XC90 v8 AWD. The ac has stopped cooling. She had the system charged and worked fine for a day or so then it started taking longer and longer for the compressor to kick in and start cooling. I took off the port for the low pressure switch and did a voltage test. It is getting 5 volts. The fuse is fine and the compressor is turning and not locked up but the clutch is not engaging. Is 5 volts right? Not sure how to bridge as it has 3 leads but only one is showing any voltage. Any ideas?

Also, hooked up coolant with built in gauge. Showing high pressure but could be a false read as the compressor is supposed to be running.

[abscate]

Measuring pressure on an un-equilibrated AC system (15 minutes running, blower high, engine 1500 rpm, doesn't tell you much. If you have to add cans of Refrigerant to get it to cool, you have a leaking component and have to find and replace it. In order of probability:

Evaporator core
Condensor
Compressor
Hoses, fittings