If you unhook both, you won't get a reading. Unhook the low side (blue) hose and see if the vacuum holds. Then hook it back up and unhook the high side hose (red). I've seen atmospheric pressure (14 psi) seep in but the system gets charged and not leak out. It depends on how strong the valve springs are. If you aren't worried about the valves, pump it down and take a 30-45 minute break and come back. If the vacuum is holding, charge it and go.

 

I was going to wait an hour as I did with house HVAC

 

I think you've mentioned that. but I'm old and while kindly, rather forgetful. The tools and hardware will be different but the techniques should be similar.

 

Good to know! I ordered kit, should be here Monday. After I read my dash out fix the wiring in going to do the AC. I'm all if I have any question. Thanks partner and hey I'm 23 and forgetful