System Operation
WARNING: This page is about a different car, the 2004 Nissan Maxima. However, it is still accessible from the selected car via links, so may be relevant.
The intake door control determines intake door position based on the ambient temperature, the intake air temperature and the in-vehicle temperature. When the DEFROST, or OFF switches are pushed or A/C switch is OFF, the unified meter and A/C amp. sets the intake door at the FRESH position.