High, I have a1999 gmc Silverado new body style that I swapped a 2006 chevy suburban 5.3 into. My problem is with the ac kicking out after about 15 seconds of run time. I have traced it back to the low pressure switch witch has continuity when the vehicle is off and when I first start it up. The ac system has just been filled so I think there is good pressure.Any help would be appreciated thanks.

 

Hook up the gauges and find out for sure