On Wed, 21 Apr 2004, Gary Goldey wrote:

> I heard 2 mechanics talking about switching out dryers and changing oil
> in compressors.  Seems to be my experience that it is overkill and
> recommended to do so because of the $$ to be made. There WILL be new
> retrofits every few years---there is a new freon to replace 134A on the
> way-

The problem, as I understand it, is the oil used with R-12 won't mix with
R-134a, and the oil used with R-134a won't mix with R-12.  It might be
okay not to change the oil in the compressor as long as some of the old
R-12 refrigerant remains...otherwise the oil won't circulate, because it
doesn't mix with R-134a.  Note that if you mix more than one type of
refrigerant in your car you'll have a hard time getting any shop to touch
it.

While new refrigerants are likely to be introduced, I don't think this
will lead to another round of retrofitting.  R-134a isn't ozone-depleting,
and I've heard of no plans to ban it, so it should remain readily
available.

David Brodbeck, N8SRE
'86 Volvo 240DL wagon
'82 VW Vanagon Westfalia Diesel