Astro a/c leak driving me nuts

2001 Astro with rear air, never had any issues until last year when compressor seal blew out. Replaced compressor, drier & orifice - evacuated/recharged and air was great last summer. This spring I flick ac on only to find out I'm completely empty on charge and found that my low pressure line going to rear ac in wheel well corroded and had a hole. Fixed that and pulled a vacuum only to see vacuum wasn't holding. I've now spent the last 2 weeks fooling with this trying to find additional leaks. I've exhausted all my means: added dye, pressurized system with shop air up to 100 psi with soap & water, used an r134 sniffer.....can't find it! If I put 100 psi in system it will hold pressure for days, but under vacuum it drains out. If I pull 30 hg and shut down, within minutes it drops to 20 hg and completely leaks out to 0 overnight.

Anybody have some clues or methods I missed?

Classic compressor shaft seal issue-holds pressure, not vacuum. That is the reason double lip shaft seals were introduced- although I would have thought aftermarket would have all been converted to double lips by now, maybe not.

I'd charge it. Run with it- and watch for dye stains- most likely on rear 3/8" liquid line at any grommets. I fix those with swagelok compression unions for aluminum. work great.

Classic compressor shaft seal issue-holds pressure, not vacuum. That is the reason double lip shaft seals were introduced- although I would have thought aftermarket would have all been converted to double lips by now, maybe not.

I'd charge it. Run with it- and watch for dye stains- most likely on rear 3/8" liquid line at any grommets. I fix those with swagelok compression unions for aluminum. work great.

Funny thing is last spring after changing the compressor I pulled a vacuum and checked it 2 days later and it never moved, so I filled it. If it is the compressor seal starting to now leak inwards it's probably a short time before it leaks outward again.

I have used the Parker A-lok (same as swagelok) double ferrules unions to fix my other van in the past with success. This time however I used the Parker CPI fittings...which are single ferrule. Even though they pass the soap test I'm wondering if I have possible vacuum leaks at those areas.