So only open up the micron gauge to vacuum not pressure. Is that right?

Okay, thanks. I researched everything AC for about 72 solid hours. I'm getting the 609 and all, so that I'm doing legit work on people's assets. I bought a JB 4 port manifold from TruTechTools and a Fieldpiece micron guage to be sure I'm at least getting through this summer with clean seals and cont...

What I mean is how many Horse Power, how many pistons, CFM ratings and things like that. Because I'm looking to spend the least right now on a used pump for auto ac services in my mobile mechanic business, and later this year get a Fieldpiece pump. So I don't know if the used ones I'm looking at are...

I'm starting out getting my ASE 609 and buying the quality equipment (affordably). I was looking at some used pumps: REFCO single piston. Appiaon G5 Twin Piston Vevor 1/2 HP I also was considering the Harbor Freight pump. It's 3 CFM for $150, but I don't think it gets anywhere close to 500 micron. T...