--snip--
>Now I don't think that there is a problem with
> the refrigerant itself - but it is a blend (80% R134, 20% HCFC) and would
> contaminate equipment used for strictly R134.
--snip--

Why would anybody put Freeze-12 in a system designed for R134a? That doesn't
make any sense.
The blend in Freeze-12 is supposed to enable you to have a proper
refrigerant charge in a converted R-12 system for strong cooling ability
without having the high head pressures that straight R-134a gives you. It's
not supposed to be a substitute for R-134a in an R-134a system.
I have read of problems with it that apparently originate in failure to
properly prepare the system for conversion; that is, if you're going to use
this stuff you'd better make damn sure to replace, replumb, clean, flush,
evacuate, exterminate, sterilize, pasteurize and so on as necessary before
you do it. However I'd think that should be considered standard procedure
for any A/C work considering the costs, the environmental issues and the
natural low tolerance of the system for contamination and poor maintenance.
Some people apparently get away with 'dumping' this or that in 'and it
works!' but I dunno... I don't have that kind of luck, if that's what it is,
but on the other hand I generally gave up on shortcuts a long time ago for
all the trouble and additional work they caused me.

Cya,
Robert