If you're not getting any cold air with the a/c on and you're getting that compressor cycling, you're low or out of freon, and you may have a leak somewhere in the system (evap, compressor). Suggest you re-charge system, add dye, run it for about a week and then go look for your leak. Start with the dreaded evaporator.

FYI for anyone interested, I have been attempting to determine with 100% certainty if I have a leak because even though I am 99% sure I am not low on freon, I still have the tick-tock sound of the compressor relay pretty much every time I have the a/c on. Based on advice/theories floated on the board, I have replaced both the a/c relay behind the glovebox, and today I replaced the pressostat (low-pressure switch). Neither one made any difference.

I have come to the completely unsubstantiated conclusion that because a) I have the better paper/carbon filter on my rig, and because I live in a nice temperate climate (Santa Barbara, CA) where the outside air temperature is usually close to where I want my inside cabin temperature, I think my compressor is just working extra hard to keep the evap from freezing up. When the family and I travel to New Mexico this summmer, presumably in a hotter environment, I will be interested in seeing if the compressor still cycles as much as it is doing now.