(Removing the air duct for the footwell)

Remove the water drain hose (1) from the bracket (2) and set it aside.

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Loosen screw (1).
Disengage the air duct (2) downwards out of the heating and air-conditioning unit.
Thread out and remove the air duct (2) in the direction of the arrow.

Courtesy of BMW OF NORTH AMERICA, INC.