I decided to tackle my a/c on my '98 c1500. New compressor, accumulator, pressure switch, orifice tube, flush, 36oz. refrigerant, 8oz. PAG oil. Flushed the evaperator and condenser with flush, then with air for 15-20 minutes each. I added 2.5 oz. of oil to the compressor(it already had 1.5oz. from the factory), and I put 4oz. in the accumulator. Blew out the lines, and hooked it all up. Put it on a vacuum pump for about an hour, then left it to see if vacuum held. 2 hours later it still had vacuum. I hooked up my gauge set and put on my first can (12oz.) of 134A. I opened up the low side and proceeded to charge the system. This is where I think I made my mistake...I forgot to turn off the low side between cans, so I think it sucked atmosphere into the system before I realized what I had done. I proceeded with the other two cans anyway. The clutch never engaged during this process, so I jumped it from the battery to facilitate charging. After the third can, with the clutch engaged (jumped) my readings are about 30 on the low side, and about 170 on the high side. When I cut the engine, both sides sit at around 85-90 psi. With the clutch jumped, at the vent it blows 55 degree air, but I think I need about 40 degree air at 80 degrees ambient temperature. Could contamination of the system by air (atmosphere) be the problem? Are my pressures too low to engage the clutch? I'm sure I'll have to go get the a/c serviced now, my only consolation being that it won't involve 400-500 dollars of labor. Thanks in advance for any replies. Steve ---------- Post added at 10:36 PM ---------- Previous post was at 10:32 PM ---------- Oh, and I forgot, the clutch seems to chirp a little when not engaged, what is the proper gap it should have?