A/C ON -> Recirculate...A/C OFF -> Fresh Air (archive)

The following has been my experience: When the A/C is ON, the system is in recirculate mode. When the A/C is OFF, the system is open to fresh air. I have also come to this conclusion based on times when I've been behind the likes of chicken trucks. ;-)

The fresh air vent is electronically controlled. When I operate the middle lever, I can hear an electronic "whir" as the vent is moved proportionally to the lever position and, if I'm at speed, I can feel the change in air flow coming through the vents.

If I have the vent open and then turn the A/C ON, I hear the "whir" as the fresh air vent is closed. After I turn the A/C OFF, I hear the same "whir" as the fresh air vent is re-opened (assuming that I did not set the middle lever to the CLOSED position while the A/C was running). This is supported by the fact that fresh air begins coming throught the vents.

Can someone shed some light on the way the A/C operates in our cars? I am confused about 2 things:

1) Is there any way to put the air in re-circulate mode when using the A/C? I have tried closing the fresh air vent(middle lever), but it appears that lever does not do anything when the A/C is on. I read the owner's manual and I believe it says that all 3 of the levers are non operational when using the A/C.

2) Is there any way to run fresh air through the condenser without having the A/C on? In other cars I have always gotten in the habit of turning the compressor off for the last few minutes of the ride home and keeping the fan on to blow fresh air through the system. Otherwise moisture would accumulate and would eventually result in a musty smell. When I switch off the compressor on the M5 it seems to switch to a whole different circuit, so the air is no longer passing through the condenser. Is this correct?

Thanks.

Sean
'88 M5
'76 2002

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