Thanks for all of those who take the time to reply to my issue. I am working on my C5 Corvette AC unit I have replace the air compressor and now I am doing a vacuum on the system after running my vacuum, for 30 minutes to an hour I cut off all the valves and I just sit there I check a couple hour later and the gauges don't move but if I leave it sitting overnight and then the gauges move now my pump is still hooked up the valves are closed off I'm wondering if it's a possible leak through my vacuum pump? Is it logical to think that the gauges should hold up completely overnight?

 

yeah with valves closed you shouldnt lose vacuum

 

If I were you I would get A/C shop to do a nitrogen leak test to see, unless you have nitrogen to pressurize, don’t use compressed air the compressor oil in air mist could cause issues down the road.

By the way they will probably do this, evacuate and weigh in R134a for a small fee, maybe $150.00 or so?

If you want them to just pressure test only, might be really low price.

 

Moved to C5 Tech.