Recently bought a 2007 535xi. Two issues I am working on, and would appreciate any input. One: there is a grinding, oscillating sound that comes at regular intervals. This noise will go away when the a/c is turned on, and return when a/c is turned off. Two: the blower motor works intermittently. It will work perfectly for several days, then go on/off, then won't work for a few days and then come back on and work perfectly again. When it's working, heat and a/c work great. I have decent tool kit and occasional access to a specialty shop where they have the autoenginuity equipment for the car. I also have the Bentley for the car, and plan is to start with some reading there this week-end. Thank you.