I have been using a Supco Micron gauge and I noticed something odd from day one.
After my vac has run for a bit, I shut off my manifold to see if the numbers go up. If I were to shut off my manifold say around 1500 microns the numbers will sometimes go down to say 750. My Micron gauge has an aux port and a vac port. I hook the hose from the low side service port into the aux side, low side hose coming out of vac side to manifold. I have both valves open when pulling a vacuum.
What is causing my numbers to drop when I close my manifold? I'm guessing that my high side has a deeper vacuum and it is siphoning the from low side causing the numbers to fall.
Discipline your child so that other parents don't have to.
We're awl pawthetic and kweepy and can't get giwrls. That's why we fight wobots.