NOt by personal experience, but by a lot of reading, the head pressure
on a 134a conversion is much greater that that of R12. There, form my
reading, expect your compressor to fail a lot sooner that might
otherwise occur.  If you stay with the R134a, when the death of your
compressor occurs, replace it with one that is made to operate with
R134a - if you can find one that fits a WBX engine.

I have had this dilema myself, as I am getting ready to rebuild my
system using a stock compressor. I have decided to stick with the R12,
or at least one of the R12 look-alikes - Duracool or some other. To use
a refigerant that is not R12 nor R134a, you must first have your rig
converted to R134a, then change it to the new R12 substitute. You must
go through the R134a stage to get to a Duracool system or other like
setup. And the system must be thoroughly flushed between changes.

I think I saw somewhere that if you go for a duracool or like
refrigerant, the goal is to wind up with a R134a valve and a R12 valve.
So you would have at the start 2 - R12 valves, next you would have two
R134a valves, then when you are done, and install th Duracool, you are
supposed wind up with both the R134a and the R12 valves. Not sure for
why though.

Regards,

John Rodgers
88 GL Driver.

Michael Diehr wrote:
> My 85 westy has a slow leak (as many do) and so about 3 years after
> my last R12 chargeup, I decided to go for a R134a conversion.   The
> shop (Harris Radiator near San Diego) did a great job, and even
> offered me a guarantee, offering to change back to R12 if I wasn't
> happy with it.
>
> Performance-wise, it's decent and I think livable.  Not ice-cold, but
> quite cool, and I like the idea of not leaking freon, so I think I'll
> stick with it.
>
> The only problem that I've noticed is that when running the AC at
> high engine rpm (3000 ish) the compressor is making a "hum" sound.
> Loud enough to be heard over engine & road noise on the freeway.   I
> can't remember if it made that sound while running on R12, since it's
> been a while, but I don't think so.
>
> Is it possible that R134 is putting more stress on my compressor and
> hence the noise?  If so, is this the sound of progress or incipient
> failure?
>
>