ACCS (Advanced Climate Control System): Aspirator
WARNING: This page is about a different car, the 2011 Infiniti QX56. However, it is still accessible from the selected car via links, so may be relevant.
The aspirator generates the vacuum by the air blown from the heater & cooling unit and draws the air of the passenger room to the front in-vehicle sensor area via the aspirator duct.
Courtesy of NISSAN MOTOR CO., U.S.A.