Water Separator

WARNING: This page is about a different car, the 2004 Nissan Quest. However, it is still accessible from the selected car via links, so may be relevant.

Check visually for insect nests in the water separator air inlet.
Check visually for cracks or flaws in the appearance.
Check visually for cracks or flaws in the hose.
Check that A and C are not clogged by blowing air into B with A , and then C plugged.

Fig 1: Inspecting Water Separator
Courtesy of NISSAN MOTOR CO., U.S.A.
In case of NG in items 2 - 4, replace the parts.
NOTE: Do not disassemble water separator.