2001 Jeep Cherokee A/C not blowing cold

We recently purchased a used 2001 Cherokee, and after several weeks we noticed the radiator had a small leak by the drain petcock. My Father replaced the radiator, but while doing so he opened one of the A/C lines from the condenser or evaporater(whichever is in front of the radiator) anyways, afterwards he got a bottle of R134 from the parts store downtown, and charged the system back up assuming that everything would be alright. Well the compressor kicks in, but there is no cold air, and the gauge that came with the r134 he bought shows "system full-do not charge" on it. I tried looking up info for him on the web but I really have no idea what it could be. It gets pretty hot in the summer down here in FL, and I don't really like the idea of my folks driving around with no A/C, and unfortunately my dad is a bit hardheaded when it comes to car things and I know he would refuse to go to an actual shop and get "ripped-off" as he would undoubtedly put it. Any ideas or suggestions as to what the problem could possibly be, would be very, very appreciated. Thank you.