From digest.v7.n349 Mon Sep 29 16:44:16 1997
From: tangen_at_nbserv2.dseg.ti.com (Eric Tangen)
Date: Mon, 29 Sep 1997 12:52:16 -0500
Subject: <10+ year old BMWs> Anemic early BMW AC
I've done just about everything else, now I'm doing
AC work...and here's what I've found out this summer
my 78 530i.
0. Hoses, dryers, and compressors are not dealer only
items. Any good AC parts shop can make hoses; dryers
and compressors are used by a wide variety of
cars and, again, available from any good AC parts
The megabuck Bosch compressor is easily replaced
by a Sanden, using a widely available bracket
kit, on both the M10 and M30 engines...
there may also be a kit for the M20 engine.
i don't know what tii owners due, as the fi pump
is right where the AC compressor would go using
the Sanden conversion bracket.
- AC work remove and replace, like just about everything
else mechanical. Just have the AC shop evacuate before
you start and fill it up again after your done. Put
the appropriate refrig lube on the threads of the
connectors when putting the thing together.
- My experience with getting a new front seal put into
a Sanden compressor hasn't been positive; get a new
compressor if you've got a front seal leak, at
least on the Sanden. A bench test doesn't check
for leaks while the compressor is rotating. (they
just dunk the compressor in a tank of liquid,
pressurize, and look for leaks...consequently,
any leaks around the shaft while the compressor
is rotating aren't found.)
- Years ago, in the tech section of the Roundel,
they published a letter from someone who had
put two electric fans in front of the AC coil
on his 530i and noted a dramatic improvement
in the AC cooling. Anyone else out there
done this? What fits?... it is very tight
Alternately, has anyone put a larger AC coil
in their BMW? Again, what fits in what models?
4. I experimented on the 530i and went for R406 instead
of R12 (www.worldserver.com/Autofrost); after working
well for two months, compressor had front seal leak; i'm
not blaming R406, compressor was new in 92 and probably
on its last legs...anyone else out there tried R406
and kept it in their system for a long period of time?
I'm now back to R12 and a new compressor for the
I thought the R406 cooled noticable better than the
R12 now in the 530i system, so i'd like to use it,
but i don't want to loose another compressor.
5. On a similiar note, i think the primary reason we BMW
owners have to replace our compressors so often (compared
to domestic cars) is that BMWs don't run the AC in
the winter...domestic cars have that bi-level climate
control that puts the AC air on the windshield and
heat on your toes...consequently, our front seals dry
out while the domestic cars don't. So run your AC in the
winter. Use it or loose it.
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