Just an update -
Got the retro kit, put the adapters on, opened the valve, put the system would only take about a 1/3lb; compressor wouldn't cycle. Checked the fuse, relay, jumped the clutch, everything good, so it had to be a blockage (not likely), or a bad leak on the hi side before the switch. Put the gauge back on, which showed the pressure had dropped. I topped it back off and shut it down. I thought I heard hissing from the pressure switch, unplugged the wire connector, and viola! The pressure bled off within a minute! Luckily Van's had one in stock; put it on, charged it up compressor came on and now our 7 mo old kiddo has cold air... $65 total. $1300 my a$$!