I gave my son an '03 525i a few years ago and it has developed a new issue lately. My son had complained that the battery would be drained flat overnight. He would disconnect the battery so he was able to start it the next day. I got in the car today and noticed that the interior fan blows even when the key is not in the ignition. I have searched the usual web sources but did not find anything that addresses this type of failure. Most of the issues concern the "Final Stage Resistor" dealing with the fan speed control. Anyone experience anything similar? Suggestions? Thanks, Myron M. Ft Worth, TX.