Nissan Maxima Service and Repair Manual: Air mix door control system

System Diagram

System Description

The air mix doors are automatically controlled so that in-vehicle temperature is maintained at a predetermined value by the temperature setting, ambient temperature, intake temperature and amount of sunload.

SYSTEM OPERATION

• The A/C auto amp. receives data from each of the sensors.
• The A/C auto amp. sends air mix door, the mode door and the intake door opening angle data to the air mix door motor LCU(s), the mode door motor LCU and the intake door motor LCU.
• The air mix door motor(s), the mode door motor and the intake door motor read their respective signals according to the address signal. Opening angle indication signals received from the A/C auto amp. and each of the motor position sensors, are compared by the LCUs in each door motor with the existing decision and opening angles.
• Next, HOT/COLD, DEF/VENT or FRE/REC operation is selected. The newly selected data is returned to the A/C auto amp.

Door Motor Circuit

Air Mix Door Control Specification

When ignition switch is ON, the A/C auto amp. continuously and automatically controls temperatures, regardless of air conditioner operational condition. When setting a target temperature with the temperature control switch, the A/C auto amp. corrects the set temperature and decides a target air mix door opening angle. The A/C auto amp. controls the air mix door, according to the target air mix door opening angle and the current air mix door opening angle, keeping an optimum air mix door opening angle. When the temperature is set at 18C (60F), air mix door is set on full-cold, and when the temperature is set at 32C (90F), it is set to full-hot.