Finally broke down and took it to the dealer to diagnose the lead I could not find.  Luckily I know the service writers so I knew I'd get a straight answer.  After about 15 minutes he came back and said they didn't find anything obvious which made me feel slightly better.  Naturally the one part they couldn't ascertain was the evaporator.

 

He basically said if it wasn't me they'd have called it an evaporator leak and quoted the customer accordingly.  So I ordered a replacement evaporator and expansion value and installed them, wasn't too bad of a job.  The evap was old an crusty but no gaping hole or otherwise that confirm the cause. 

 

So now I put it back together with new O-rings and a new receiver/drier too and hook up the vacuum and won't go past 18 Hg.  Memory serves I should get to about 22 Hg.  Anyway I shut the pump off and it loses vacuum immediately.  I double check everything is tight try it again and its the same.  So I disconnect the lines and remove the expansion valve to be sure I didn't miss something.  All looks good.  I try again and got real close to the valve and you can actually hear the sucking sound when the pump is on.  Spray some soapy water on it and it slowly pulls the water in b/t the valve and where the lines bolt in.

 

I'm really at a loss as to why I can't create a tight seal.  I matched up the o-rings with ones from my kit and they are  pretty good matches, everything bolts up nice and tight, yet I'm sucking air when vacuuming.

 

Any ideas?  Thanks!

 

 

I've matches o rings in the past that resulted in leaks. The o rings tend to stretch and stay stretched. Match the line instead. The oring should need to be stretched slightly to fit. Also make sure you are lubricating the o ring. That might do the trick. It would also be a good idea at this point to put in a bit of die to spot and future leaks.

I would lean towards using the UV dye with partial charge, rather than letting the vacuum suck in soapy water.

Thanks.  When I shut off the pump I can actually hear a hissing coming from the valve area.  it has to be the o-rings, correct?

Probably first guess. Check for cracks and the like also. With it leaking that bad, it might be easier to find with pressure.