WARNING: This page is about a different car, the 2006 Nissan Pathfinder. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Ducts - Front Heater And Cooling Unit Assembly
Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 2: Identifying Ducts - Rear Heater And Cooling Unit Assembly