Hi, I have a 2001 540i with around 75,000 miles. The HVAC system is the IHKA (auto climate contro). Over recent weeks I've noticed some irregular behavior from the climate cotrol where the fan seemed to run at speeds much different from the indicated fan settting -- usually faster occassionally not at all. I've assume that this was a final stage resistor problem and planned to replace it.

A couple of days ago, a new noise started in the dash that I can best describe as a buzz or hum that's loud enough to be felt at my right leg and sounds a little like a rumble strip on the highway. If I had to guess, I'd suspect a stepper motor or a damper thats vibrating in heavy flow. The closest one to my leg is the fresh air stepper.

So, my question is whether or not any of you have noticed these symptoms before the final stage resister quit in your cars, or is this possibly an electical problem of a different nature? Anyone have problems with specific blower components that make enough noise to be a feelable vibration? Any good troubleshooting advice?

Thanks. I'm new to the forum, and appreciate the depth of information in the archive.

-Damian (cuestix411)