Thought I'd reply back finally... I did what Tim suggested. System only had a little over a pound when I evacuated it. Pumped it down for about 15 minutes let it sit for another 10 minutes, and was satisfied it didn't have a serious leak. Once we got the full charge 48oz we ended up with 42 degree v...

Hi, thanks for any help... 2003 Envoy XL dual AC manual control 4.2L engine cooling has grown weak over last year or two. System has never been opened 245k miles 85 degree outside temp system would short cycle at any speed above idle gauge pressures 40psi and 160psi at idle anything above idle low s...