Many thanks for sharing this information with us.
I own a 2001 530i with 63K miles. A few months ago, I noticed strange behavior with the A/C and heater. Sometimes they work and sometimes they don't. When they work, I can't control the speed of the fan (but I was able to turn off the unit). The dealer (Stevens Creek BMW) asked $200 to replace a "controller" (they said if that does not fix the problem, they will replace the whole unit for $1,000+). I declined the dealer's offer to replace the controller and searched online about known problems with the A/C and heater - and I came across your article. After looking at your article and the photos, I was convinced that the problem will be resolved by replacing the FSU unit. So, per "domiguy" suggestion, I ordered the FSU unit from AutoHaus for $63, and replaced the unit per your instructions. Now I am able to control the fan.
While replacing the FSU, I found it difficult removing the wire and sliding the old FSU out, because of a cover right below the glove compartment. In your photo that says "follow the wires... FSU up there", I suggest you also show how to remove the cover below the glove compartment so that you have more room to work. I was not able to remove the cover, so I struggled to replace the unit.
Overall, your instructions are great. Many thanks once again.
Last edited by bimmer01; 01-13-2007 at 03:04 PM.