I converted to 134a, in my '85 Westy, several years ago.  I changed the
receiver dryer, removed and drained the compressor, flushed the system,
but kept the old expansion valve.  Of course, I put in new O-rings where
the old ones were disturbed.

It blows acceptably cold (sorry I don't have the temperature numbers)
... cold enough freeze up on humid days ... but I'm considering changing
to something like duracool just to get the head pressures down from
those seen with 134a.

Yours is not cooling anywhere near where it should.

Mike

Bob Mac wrote:
>   I just converted my AC to 134a on my 84 westy. I put a thermometer in
> the air duct and it reads 63 degrees. It seems to me that it should be a
> little colder than that. What do the masses think. Or is this about all
> i can expect out of it.
>