which refrigerant?

[engine]

Cool-if it's all new, then just throw it in a vacuum until you can pull 28-30 inches, then if it holds with pump off for at least 3 hours with no drop in vacuum, I'd say you're good to go! -Jabin

I actually like to pull vacuum to 500 microns or deeper. But with Automotive AC rubber hoses, I'm not sure if that is possible. I may get there, but I'm not sure how "non-permeable" the hoses actually are. But I guess if I'm under 1000 microns, it's good enough.