A/C compressor randomly cutting off
 

While the car is running with the A/C on, I can hear the compressor cutting off and on at random times. Is this something with the compressor itself, or could it be a pressure sensor?

sounds like pressure or the compressor itself.. I really dont know though. I would check the refrigerant.

Low refrigerant will definitely cause this - at least on a crappy Ford Tempo I once owned and a slightly less crappy Volvo 240 that came afterward.

I haven't charged the AC on a Boxster, but I assume it's DIYable, and it's a cheap first troubleshooting step since you can buy recharge kits at Target and WalMart...

Its definatly not anything you want to do on your own (DIY). You would need to take it to a shop that has the proper AC refill gauge/hose set, too much pressure/overfilling can cause leaks and failure of your AC system, Too little refridgerant/compressor oil and the compressor can fail.

Most likely a pressure switch or over or undercharged system. Have a shop hook it up to an ac machine to check pressures first. Then check the pressure switch.

Best of luck,
jd