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 shop.

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.

1. 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.

2. 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.)

3. 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 up there.

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 time being.

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.

eric tangen
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