AC systems should be filled by volume. R-134 gets filled to only 80% of
the fill required for R-12. The only proper way to fill R-134 is to
evacuate the system and measure the quantity going in. One common
problem with the later Vanagon AC's is the condenser clogging
internally. The flat tubes trap anything that doesn't belong. A reverse
flush will often get the rubber pieces, compressor parts and rust out.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
Of Roger Sisler
Sent: Monday, April 17, 2006 3:29 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: AC convert

134a works at pressures about 20 percent higher than r-12. Look for
about
250 psi high side,I believe. Did you put enough 134a in? I hear that
folks
who convert to 134a say that it will work ok most times.That expansion
valve is origional? It is a r-12 valve. Swap it for a 134a valve.A
refrigerant(besides r-12) that works at r-12 pressures let  you keep the
valve.