Automotive Air Conditioning Information Forum

I need the help of more experience on this field, the problem I have is My Cadillac Escalade has new compressor, new condenser, new receiver (dryer), it holds vacuum for almost 1:30 hour but do not hold gas pressure. I thought problem was with fitting because gauge were not installed after charging the system but I also then changed high and low fitting valves and still leaking the gas but not when vacuum is hold at steady 30.

Bear in mind that a system can leak under pressure yet still hold a vacuum. How fast did the refrigerant leak out...within minutes, hours, days, weeks, etc.?

I believe what you said is that gauges were not installed after recharging. Did you charge it by weight with the gauges attached and with an accurate refrigeration scale? If not, how did you charge it? Did you add any oil, plus a small amount of UV dye? The dye would help in diagnosing any leaks now.

What were the gauge readings?

You mentioned that you changed the Schrader valves at the low-pressure and high-pressure ports with new parts. Did you put the original caps back on after ensuring that the internal o-rings were intact? Or even better, did you replace the caps with new ones? The caps actually do the sealing, not the Schraders. If you covered that, then the system still has a leak someplace else, possibly in the lines to the rear evaporator if it has one back there. One of the new parts might have a defect as well, like the compressor front seal.

It's also possible that the front evaporator case has accumulated leaves and dirt over the years, which can hold moisture, cause corrosion on the coils, and an evaporator leak.