Michael,

Every spring for three or four years, I had to add about a pound of R12 to
my system (slow leak at the front compressor seal).  It finally got too
expensive to replace the freon so I started looking into converting to 134A.
www.aircondition.com has an ac discussion board similar to the Vanagon list.
  A real conversion to R134A needs a lot of parts to really make it work
correctly.  R12 compressors are different than R134A compressors because of
the much higher operating pressures for R134A.  Freeze-12(www.freeze12.com)
is sort of advertised as a drop in replacement for R12. Freeze-12 does NOT
carry the oil used for R12 very well and will probably screw up your
compressor unless you add a little ester oil. It operates at a higher
pressure than R12 but not as high as R134A.  My system lasted all last
summer (in El Paso) and needed the same amount of Freeze-12 last month as it
used to need of R12.  I had my system recovered of all freon, vacumned out,
a little ester oil added, and about 41 oz of Freeze 12 installed.  The
person that performed the work is licensed and used professional gages and
charged by pressure readings.

I was able to get Freeze-12 at a good price, but it can be difficult to
find.  When my compressor finally goes, instead of getting a new Sanden R12
compressor for at least $299 plus shipping and labor, I will use one of the
new Sanden R134A compressors, a new reciever/dryer, all new O-rings, new
expansion valve, etc.

If it wasn't extremely illegal to do so, using Freeze-12 to top off your R12
would work.

Randy Herd
86 GL Weekender
68 Kombi
98 Jeep Cherokee

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