Saturn Repair: ac problem, saturn lw300, proper tools

Question
I have a 2001 Saturn LW300 with a v6 engine.  The ac stopped working yesterday.  It still blows hot air through the vents but no cold air.  The dealership said that the compressor is shot.  Other posts on the web say to try to add R134a and see what happens.   I bought a can and conected it to what I thought was the low side (near firewall on a big tube as that the other port was near radiator  and had a small tube)  The gauge on the can read 120 psi which put it in the danger zone.  Did I connect to the proper port?  Whats the psi supposed to be?  Should I conyinue to try to add R134a or just take it to a mechanic?

Answer
It sounds like the compressor may be bad or another component in the system. You definitely have a good amount of R134a in the system so adding more will only do more damage. I would have the dealer repair the compressor issue. They have the proper tools to deal with the refrigerant.