Well, excuse me for being a pansy, but I'd like my A/C to work...

Anyway, yesterday I checked the system, and this is what I found. With the engine running and A/C on, pressure would rise from 25 to 45 psi and then drop back to 25psi. When it would go up to 45, I would hear a clicking sound from what I'm guessing is the compressor, and then the guage would drop back to 25. I tried adding some refridgerant, but it didn't help. It's still blowing just hot air.
Ideas...?