The lines which run under the van to the Condenser upfront are the biggest suspect for leaks, and can leak over the entire area, as they really were not designed for R134 and are now 23 years old.  

Start with replacing these with the latest technology, and of course a new receiver dryer.  Put a vacuum on the system and see if it holds for a week or so, before you put R134 back into the system.

Good luck!

Jack R.
84 Westy

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Dave Mcneely
Sent: Tuesday, January 21, 2014 4:25 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Air Conditioning help

My 1991 Volkswagen Vanagon GL Campmobile with factory air conditioning and a 2.1 liter engine (159k miles) loses refrigerant over the course of a summer.  It had it converted to R134a two springs ago.  It got all new fittings, the system was flushed, and new proper lubricant for R134 was added.  It cooled wonderfully well, but by summer's end it was not doing so, despite two shops claiming not  to be able to determine that it was leaking.  They reported that with a "leak down test" over 24 hours, it held proper pressure.

So, next spring it needed recharging again, and again, "leak down test reveals no leak."  By summer's end, it was not cooling.  Recharging resulted in the thing cooling marvelously, air temperature from the plenum being around 48 F.  So, what do I do now?  I plan to use the camper this spring, summer, fall and will need air conditioning for some trips through the plains and Southwest.

Help!

David McNeely