a/c clutch doesn't stay engaged

Wow, I was just speaking to a colleague about one of these unusual vehicles today, with the supercharged engine. Anyway -- When the compressor is cycling quickly like that, it is usually due to insufficient charge / system pressures. What really needs to happen is that a set of gauges at the very least and a R134a recharging station ideally can be hooked up to the system to vacuum test for any leaks and recharge the system with the proper refrigerant amount. Anything other than that -- you're flying blind. I would guess any number of concerns could be present with your 24 year old vehicle -- leaks from just about anywhere including hose o-rings, a compressor that has a clutch or coil that is worn or inoperative, a cycle switch issue, and on and on... Testing is more than just trying to recharge a system. Good luck!