Brian,
  I have to agree with Cary, A/C systems need special tools and
equipment to be done right.  As far as converting to R134a, VW has a
bulliten out for just that.  The kits costs about 200 bucks and  DOES
NOT need a new compressor. Replace the reciver drier, change the
compressor oil, R134a adapters and a few o-rings is all that is needed.
VW says that you should vacuume the system down for at least 30
minutes.  A wholesale customer of mine says he vacuumes it for at least
6 hours. That dries the system so much that you could almost reuse the
reciver drier.
  Years ago when r12 was pennys a pound unstead of dollars per ounce,
DIYers could add freon to there A/C every few months without to much
problems, but the EPA says that we are destroying the environment so R12
is bad.   Just so everyone knows, today cost of R12 is 49.95 per pound
and R134a is 17.50 per pound. So if you want to spend a couple hundered
dollars now, VW has a kit to update your vanagon, or and VW made after
1985, to R134a. Then next year if you need a recharge, the cost will be
less than a weekend camping trip.

PS. Vanagons take 3.4lbs of R134a.
--

                          -Jim DiGennaro
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