Upstairs A/C unit wasn't cooling and we discovered our suction line wasn't sweating. We have now had 2 technicians over and we still don't have cold air.

Technician #1- Said unit was low on *****. Since he didn't notice any leaks outside he went to look inside. He said the oil residue on the coils showed there's a leak in the coil and the only option is replace the entire system because he no longer can install a coil for an R-22 system.

Technician #2- Said we were low 1 lb. of *****. Tested the air coming out of vents before charging and it was 70 degrees. Air going into system was 80 degrees. Used a detector and found ***** leaking from a joint that had a nut that was loose. He tightened the nut and couldn't detect a leak anymore. He charged the system and said the Superheat was reading 10. He was dumbfounded that the air temperature coming out of the vents didn't change at all, and the suction line still isn't sweating.

Obviously, something is still not working. Any ideas on what the problem is?