NISSAN PATROL 1998 Y61 / 5.G Heather And Air Conditioner Repair Manual

Introduction
AIR CONDITIONER LAN SYSTEM OVERVIEW CONTROL SYSTEM
The LAN system consists of auto amp., air mix door motor and mode door motor.
A con®guration of these components is shown in the diagram below.
Features
SYSTEM CONSTRUCTION (LAN)
A small network is constructed between the auto ampli®er, air mix door motor and mode door motor. The auto
ampli®er and motors are connected by data transmission lines and motor power supply lines. The LAN net-
work is built through the ground circuits of the two motors.
Addresses, motor opening angle signals, motor stop signals and error checking messages are all transmitted
through the data transmission lines connecting the auto ampli®er and two motors.
The following functions are contained in LCUs built into the air mix door motor and the mode door motor.
+Address
+Motor opening angle signals
+Data transmission
+Motor stop and drive decision
+Opening angle sensor (PBR function)
+Comparison
+Decision (Auto ampli®er indicated value and motor opening angle comparison)
RHA439G
RHA440GA
DESCRIPTIONAUTO
HA-49

Operation
The auto ampli®er receives data from each of the sensors. The ampli®er sends air mix door and mode door
opening angle data to the air mix door motor LCU and mode door motor LCU.
The air mix door motor and mode door motor read their respective signals according to the address signal.
Opening angle indication signals received from the auto ampli®er and each of the motor position sensors are
compared by the LCUs in each motor with the existing decision and opening angles. Subsequently, HOT/
COLD or DEFROST/VENT operation is selected. The new selection data is returned to the auto ampli®er.
Transmission data and transmission order
Ampli®er data is transmitted consecutively to each of the door motors following the form shown in ®gure below.
Start: Initial compulsory signal sent to each of the door motors.
Address: Data sent from the auto ampli®er is selected according to data-based decisions made by the air mix
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 and mode door motor.
Error data can be related to the following problems.
+Abnormal electrical frequency
+Poor electrical connections
+Signal leakage from transmission lines
+Signal level ¯uctuation
Stop signal: At the end of each transmission, a stop operation, in-operation, or internal problem message is
delivered to the auto ampli®er. This completes one data transmission and control cycle.
RHA441GA
DESCRIPTIONAUTO
Features (Cont'd)
HA-50

Air mix door control (Automatic temperature control)
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.
Fan speed control
Blower speed is automatically controlled based on temperature setting, ambient temperature, in-vehicle
temperature, intake temperature, amount of sunload and air mix door position.
With FAN switch set to ``AUTO'', the blower motor starts to gradually increase air ¯ow volume.
When engine coolant temperature is low, the blower motor operation is delayed to prevent cool air from ¯ow-
ing.
Intake door control
The intake doors are automatically controlled by: The temperature setting, ambient temperature, in-vehicle
temperature, intake temperature, amount of sunload and ON-OFF operation of the compressor.
Outlet door control
The outlet door is automatically controlled by: The temperature setting, ambient temperature, in-vehicle
temperature, intake temperature and amount of sunload.
Magnet clutch control
The ECM (ECCS control module) controls compressor operation using input signals from the throttle position
sensor and auto ampli®er.
Self-diagnostic system
The self-diagnostic system is built into the auto ampli®er (LCU) to quickly locate the cause of problems.
RHA442G
DESCRIPTIONAUTO
Features (Cont'd)
HA-51

Overview of Control System
The control system consists of input sensors, switches, the automatic ampli®er (microcomputer) and outputs.
The relationship of these components is shown in the diagram below:
RHA732G
DESCRIPTIONAUTO
HA-52

Control Operation
Display screen
Displays the operational status of the system.
AUTO switch
The compressor, intake doors, air mix door, outlet doors, and blower speed are automatically controlled so
that the in-vehicle temperature will reach, and be maintained at the set temperature selected by the operator.
Temperature dial (Potentio Temperature Control)
Increases or decreases the set temperature.
OFF switch
The compressor and blower are OFF, the intake doors are set to the outside air position, and the air outlet
doors are set to the foot (80% foot and 20% defrost) position.
FAN switch
Manual control of the blower speed. Four speeds are available for manual control (as shown on the display
screen):
low
, medium low, medium high, high
RECIRCULATION switch
OFF position: Automatic control resumes.
ON position: Interior air is recirculated inside the vehicle.
DEFROSTER switch
Positions the air outlet doors to the defrost position. Also positions the intake doors to the outside air position.
MODE switch
Control the air discharge outlets.
RHA727G
DESCRIPTIONAUTO
HA-53

FRESH switch
OFF position: Automatic control resumes.
ON position: Outside air is drawn into the passenger compartment.
A/C switch
Manual control of the compressor operation. When the A/C switch indicator illuminates, compressor operation
is being carried out.
DESCRIPTIONAUTO
Control Operation (Cont'd)
HA-54

Component Location
ENGINE COMPARTMENT
RHA697G
TROUBLE DIAGNOSESAUTO
HA-55

PASSENGER COMPARTMENT
RHA698G
TROUBLE DIAGNOSESAUTO
Component Location (Cont'd)
HA-56

Circuit Diagram
THA153
TROUBLE DIAGNOSESAUTO
HA-57

Wiring Diagram Ð A/C, A Ð
YHA159
TROUBLE DIAGNOSESAUTO
HA-58