2000 528i E39 Battery

[shutchomatic]

Well I finally purchased my first BMW and am already experiencing some of the interesting issues that can occur (like ABS Module, FSU, etc.)

I have found many postings about the FSU problem (since my battery was going dead) and have replaced the FSU. The problem is still there and I am wondering if there is something else (other than a DOA FSU) that could be causing this. I hear what sounds like a low speed fan noise coming from behind the AC control panel.

Any information is greatly appreciated, this forum has already helped me a great deal.

[shutchomatic]

Pulled a code 16 from the AC Control Unit and now know what has been causing the battery to go dead and what is causing the small fan noise in the AC control panel.
The internal temperature sensor, small fan that pulls air across the sensor to determine the cabin temperature.
Nice little $150.00 part.

[witeshark]

Thanks for sharing the answer!