No air flow on the floor BMW X5 2002

To clarify what you telling us you have good aiflow out of the defrost setting and the panel setting just not the floor? If I under stand you right that sounds to me like you have an issue with a stepper motor for the floor control that is not responding/ has failed. Thats one possible issue, the other is your climate control module (IHKA) has stopped outputting a signal to that stepper motor for the floor. If you replace the stepper motor for the floor you will have to have the IHKA module coded to accept the new stepper motor. Hope this helps.

You will need to have someone with the correct scanning equipment scan and diagnose your climate control system. It will cost you much less than throwing parts at the car.