A/C poor cooling

Today it got warmer outside, so I turned on the A/C on our 95 GC V6 and it wasn't cooling the air. I also noticed the compressor was continously cycling on and off for like evey 5 seconds or so. Is that a sign of low refrigerant? How can I check if the system is low in refrigerant?

bump...

All the Chilton Manual gives me is how to remove the Compressor and some safety precautions.

Has the same thing on our 94. They refilled the refrigerant with dye tracer and located the leak at 2 O-rings. But yeah, you probably have a leak somewhere