Not to raise another big long lengthy debate on R134a vs Freeze 12 - and
all the rules and tech stuff not withstanding - from what I can digest
from it all is that so far as operation goes - use of R134a introduces a
much greater head pressure to the system than does Freeze 12 - which
approximates the old R12 - and this higher R134a  head pressure is what
sends Vanagon era compressors to early graves. Other than that - they
appear to cool about the same.

Just my $0.02 from reading about this subject.

John Rodgers
Clayartist and Moldmaker
88'GL VW Bus Driver
Chelsea, AL
Http://www.moldhaus.com

On 6/19/2010 6:20 PM, Loren Busch wrote:
>   RE: Substitutes for R12
> This subject was explored in every possible way a few years ago on this
> list.  Being to lazy to bother to look for the thread or the notes I kept at
> the time I'll try to summarize from memory.
> First, R134 is what is recommended by VW, full service bulletin on it.
> Second, when changing to R134 adapters are screwed on to the connections to
> the original AC.  Those adapter are needed because of the fittings used with
> R134 AND to indicate that the change has been made. Now, for the Freeze 12
> (and a bunch of other such).  There were several strong advocates of  Freeze
> 12 for use in the Vanagon.  And it apparently works quite well.  But chasing
> down a bunch of links that people posted provided the reason that it is not
> 'approved'. It contains flammable gases in minute quantities and has not
> been tested to the point that is required for official approval.  And on top
> of that it is specifically illegal for use in passenger cars in a number of
> States.  BUT is is okay for non highway use like in farm equipment, heavy
> construction equipment, etc.  That's why it is readily available especially
> around farming communities.
> Another related note on this subject, based on conversations with a close
> friend that at the time had been running his own auto repair shop for many
> years.  If you load your AC system up with the stop leak gunk, and are
> honest about it, then most shope won't touch your AC system.  This is
> because  that stuff totally disables the refrigerant recovery systems that
> legit shops must use to recover the coolant rather than release it to the
> atmosphere.  It had cost him big bucks to get his equipment fixed after such
> an incident and the second time it happened he quit servicing AC.  Since
> then the makers of the AC recovery equipment have added a detector or some
> sort to try to avoid this problem but in talking to one service shop just a
> couple of years ago they said the same thing.  If you've added a 'stop leak'
> to the AC they won't work on it.
>
>
>