Infiniti I30 (A33). Manual — part 515

IACV-AAC CONTROL SYSTEM

=NHHA0165

Operation

NHHA0165S02

When the air conditioner is OFF, the ECM detects the load applied to the engine, and controls the IACV-AAC
valve to adjust the engine idling speed to the appropriate rpm by supplying additional air from the IACV-AAC
valve.
When the air conditioner is ON (A/C relay is ON), refrigerant-pressure sensor converts refrigeration-pressure
on the high pressure side into the voltage value, which is output to ECM which protects refrigeration cycle and
control idle speed by the output voltage data, and additional air is supplied to the engine. If the appropriate
engine speed is not reached, the IACV-AAC valve supplies the additional air required to increase the engine
rpm.

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DESCRIPTION

V-6 Variable Displacement Compressor (Cont’d)

HA-19

Component Layout

NHHA0166

RHA349H

DESCRIPTION

Component Layout

HA-20

Introduction

NHHA0167

AIR CONDITIONER LAN SYSTEM OVERVIEW CONTROL SYSTEM

NHHA0167S01

The LAN system consists of auto amp., air mix door motor, mode door motor and intake door motor.
A configuration of these components is shown in the diagram below.

RHA439GC

Features

NHHA0168

SYSTEM CONSTRUCTION (LAN)

NHHA0168S01

A small network is constructed between the auto amplifier, air mix door motor, mode door motor and intake
door motor. The auto amplifier and motors are connected by data transmission lines and motor power supply
lines. The LAN network is built through the ground circuits of the three motors.
Addresses, motor opening angle signals, motor stop signals and error checking messages are all transmitted
through the data transmission lines connecting the auto amplifier and three motors.
The following functions are contained in LCUs built into the air mix door motor, intake door motor and the mode
door motor.

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Address

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Motor opening angle signals

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Data transmission

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Motor stop and drive decision

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Opening angle sensor (PBR function)

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Comparison

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Decision (Auto amplifier indicated value and motor opening angle comparison)

RHA350H

Operation

NHHA0168S0101

The auto amplifier receives data from each of the sensors. The amplifier sends air mix door, mode door and
intake door opening angle data to the air mix door motor LCU, mode door LCU and intake door motor LCU.
The air mix door motor, mode door motor and intake door motor read their respective signals according to the
address signal. Opening angle indication signals received from the auto amplifier and each of the motor posi-
tion sensors are compared by the LCUs in each motor with the existing decision and opening angles.
Subsequently, HOT/COLD, FRESH/RECIRCULATION or DEFROST/VENT operation is selected. The new
selection data is returned to the auto amplifier.

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DESCRIPTION

Introduction

HA-21

RHA351H

Transmission Data and Transmission Order

NHHA0168S0102

Amplifier data is transmitted consecutively to each of the door motors following the form shown in figure below.
Start: Initial compulsory signal sent to each of the door motors.
Address: Data sent from the auto amplifier is selected according to data-based decisions made by the air mix
door motor, intake door motor and mode door motor.
If the addresses are identical, the opening angle data and error check signals are received by the door motor
LCUs. The LCUs then make the appropriate error decision. If the opening angle data is normal, door control
begins.
If an error exists, the received data is rejected and corrected data received. Finally, door control is based upon
the corrected opening angle data.
Opening angle: Data that shows the indicated door opening angle of each door motor.
Error check: Procedure by which sent and received data is checked for errors. Error data is then compiled.
The error check prevents corrupted data from being used by the air mix door motor, mode door motor and
intake door motor. Error data can be related to the following problems.

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Abnormal electrical frequency

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Poor electrical connections

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Signal leakage from transmission lines

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Signal level fluctuation

Stop signal: At the end of each transmission, a stop operation, in-operation, or internal problem message is
delivered to the auto amplifier. This completes one data transmission and control cycle.

RHA352H

Air Mix Door Control (Automatic Temperature Control)

NHHA0168S0103

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

DESCRIPTION

Features (Cont’d)

HA-22