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