sensor ISUZU TROOPER 1998 Service Owner's Manual

1BÐ74 AIR CONDITIONING
FUNCTIONS AND FEATURES
¥ Automatic interior temperature control
This function enables to maintain the interior temperature at the level specified from the temperature
control switch despite of changes in factors such as vehicle speeds, outside air temperature and number
of passengers.
¥ Maximum cooling and heating function
You can select FC (Full cool, namely maximum cooling temperature) or FH (Full heat, maximum heating
temperature) from the temperature control lever.
¥ Automatic air flow control
Air flow is automatically and consecutively fine tuned according to the specified interior temperature and
changes in aperture of the heater unit mix door.
¥ Mode (blow port) control
This function automatically selects either one of the VENT, BI-LEVEL, FOOT or DEP mode for the blow
port according to changes of temperature on the blow port. Using the mode switch allows you to select a
desired blow port manually.
¥ Intake (switching between the fresh air intake and circulation of interior air) control
The intake (switching between fresh air intake and circulation of interior air) mode automatically selects
either FRESH (fresh air intake), MIX or RECIRC (interior air circulation) according to changes of the blow
port temperature. Using the intake switch allows you to select a desired intake port manually (in the
manual operation, FRESH and RECIRC modes alone are available). Pressing the DEF (defrost) mode
switch selects the FRESH (fresh air intake).
¥ Cooler start-up timing control
This function is used for maintaining the air flow at "LOW" level until the evaporator is sufficiently cooled
down. It is intended to prevent a large volume of hot air being blowing into inside of a vehicle when the
cooler is turned on in hot summer season.
¥ Heater start-up timing control
This function is used for maintained the air flow at "LOW" level and also for maintaining the defrost
mode until temperature of coolant in the heater core is sufficiently heated. It is intended to prevent a
large volume of cool air being blown into inside of a vehicle when the heater is turned on in cold winter
season.
¥ Solar radiation quantity offset control
The photodiode on the solar radiation sensor determines solar radiation quantity accurately to offset
interior temperature quickly.
¥ Switch position storing function
This function is used for storing switch positions being selected in the immediately preceding operation,
namely the last time the ignition has been turned off. It simplifies the setup procedures when restarting
the system.
¥ Self-diagnosis function
The self-diagnosis function turned on from the panel switch makes your troubleshooting easier (for detail
of this function, refer to the section titled "Self-Diagnosis").

AIR CONDITIONING 1BÐ75
FULL AUTO display
INTAKE indication
(LED)
(switching between
fresh and interior air)
MODE indication
(LED) (Blow port)
AC display (LED)
FAN indication (LED)
FAN KNOB
AUTO SET
REC FRESH SWITCH
TEMP LEVER
(temperature control)
MODE SWITCH
(blow port selection)
AC SWITCH
IN CAR SENSOR
AMBIENT SENSOR
SUN SENSOR
DUCT SENSOR
MIX ACTUATOR
POTENTIOMETER
MODE ACTUATOR
POTENTIOMETER
AIR MIX DOOR
MODE DOOR
INTAKE ACTUATOR
RECINTAKE DOOR
FAN MOTORPOWER
TRANSISTOR
AUTOMATIC HEATER/AIR CONDITIONER CONTROL UNIT (with the built-in micro-computer)
MAX HI RELAY
PRESSURE
SWITCHAIR CONDITIONER
THERMO RELAY
COMPRESSOR
SWITCH MAGNET
CLUTCH
PCM
PRESSURE
SWITCHAIR CONDITIONER
THERMO RELAYMAGNET
CLUTCH
(4JX1engine)
MIX FRESH
FULL AUTOMATIC AIR CONDITIONER BLOCK DIAGRAM
F01RY00009

1BÐ76 AIR CONDITIONING
10
71
1
5
6
12
13
11
2
3
4
8
9
852RY00001
Legend
(1) Liquid Line (High Pressure Pipe)
(2) Pressure Switch
(3) Ambient Sensor
(4) Receiver Drier
(5) Discharge Line (High Pressure Hose)
(6) Suction Line (Low Pressure Hose)(7) Compressor
(8) Condenser Assembly
(9) Drive Belt
(10) Compressor Bracket
(11) Drain Hose
(12) Evaporator Assembly
(13) O-ring
AIR CONDITIONING PARTS
6VE1 (RHD)

AIR CONDITIONING 1BÐ77
910
6
12
13
3
2
4
5
7
8 11
1
852RY00002
Legend
(1) Liquid Line (High-Pressure Pipe)
(2) O-ring
(3) Discharge Line (High-Pressure Hose)
(4) Pressure Switch
(5) Receiver Drier
(6) Ambient Sensor(7) Condenser Assembly
(8) Drive Belt
(9) Compressor
(10) Drain Hose
(11) Suction Line (Low-Pressure Hose)
(12) Evaporator Assembly
(13) A/C Switch
6VE1 (LHD)

1BÐ78 AIR CONDITIONING
107 13
65 12
14
1115
2 1
3
9 8
4
852RY00003
Legend
(1) Liquid Line (High-Pressure Pipe)
(2) Pressure Switch
(3) Receiver Drier
(4) Ambient Sensor
(5) Compressor Bracket
(6) Discharge Line (High-Pressure Hose)
(7) Suction Line (Low-Pressure Hose)(8) Compressor
(9) Condenser Assembly
(10) O-ring
(11) Insulator Pipe
(12) Suction Line (Low-Pressure Pipe)
(13) Drain Hose
(14) Evaporator Assembly
(15) A/C Switch
4JX1 (RHD)

AIR CONDITIONING 1BÐ79
852RY00004
107
65
12
2 1
3
9 8
11
4
Legend
(1) Liquid Line (High-Pressure Pipe)
(2) Pressure Switch
(3) Receiver Drier
(4) Ambient Sensor
(5) Compressor Bracket
(6) Discharge Line (High-Pressure Hose)(7) Suction Line (Low-Pressure Hose)
(8) Compressor
(9) Condenser Assembly
(10) Drain Hose
(11) Evaporator Assembly
(12) A/C Switch
4JX1 (LHD)

1BÐ84 AIR CONDITIONING
OVERVIEW OF CONSTRUCTION,
MOVEMENT AND CONTROL OF MAJOR
PARTS OF FULL AUTOMATIC AIR
CONDITIONER SYSTEM
Automatic Heater/Air Conditioner Control Unit
Equipped with the built-in micro-computer, this
control unit operates on signals from sensors and
input signals from switches to offer total control of
the blower fan, and actuators used for the mode
door, intake door and air mix door.
Its self-diagnosis function enables quicker access to
a failed part and its more accurate troubleshooting.
In Car Sensor
It is a sensor used for detecting room temperature
of a vehicle. This sensor converts a given room
temperature into a resistance value before entering
the data to the automatic heater/air conditioner
control unit.
This in car sensor unites the power driven aspirator
and the motor fan so that a small amount of room
air may be constantly fed to the sensor.
This sensor is provided on the control panel.
Legend
(1) In Car Sensor
(2) Full Automatic Air Conditioner Control UnitAmbient Sensor
This sensor is used for detecting temperature
outside the vehicle. It converts a given outside air
temperature into a resistance value before entering
the data to the automatic heater/air conditioner
control unit.
Thermal effects from the condenser and radiator
during idling after a run can be measured and offset
the automatic amplifier.
This sensor is provided on the side plate situated at
upper right side of the condenser.
Legend
(1) Ambient Sensor
(2) Condenser Assembly
¥ Duct Sensor
The sensor is the sensor to detect temperature
change of the side of evaporator blower coming
by fresh recirculation of intake door or "on" "off"
of compressor.
The temperature is converted to resistant rate.
And it works as thermostat to control to prevent
freezing of evaporator.
This sensor is installed in the upper case of
evaporator.


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21
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21
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AIR CONDITIONING 1BÐ85
Legend
(1) Duct Sensor
(2) Evaporator Assembly
(3) Amplifierblock
In Car Sensor
It is a photodiode used for detecting quantity of
solar radiation. This sensor converts the offset
signal generated by changes in the interior
temperature (which results from fluctuations in
solar radiation) into photoelectric current to enter
into the automatic heater/air conditioner control
unit.
This sensor is provided at top of the defroster grill.
Legend
(1) Sun SensorActuator
The actuators are power driven type containing a
small motor. Receiving output current from the
automatic heater/air conditioner control unit,
actuators drive the heater and blower unit mode
doors.
Actuators consist of the mode actuator used for
switching the mode (blow port selection), the mix
actuator used for changing aperture of the air mix
door, the intake actuator used for switching the
intake mode(fresh air/interior air).
Legend
(1) Mix Actuator
(2) Heater Unit
(3) Mode Actuator
(4) Blower Unit
(5) Intake Actuator
The actuator changes the motor speed using the
gear and drives each door rotating the output axis
united with the sliding contact.
2 31
860RX013
1
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This illustration is based on RHD
2
5
431
860RX012
This illustration is based on RHD

1BÐ88 AIR CONDITIONING
OVERVIEW OF AUTOMATIC CONTROL OF
FULL AUTOMATIC AIR CONDITIONER
The full automatic heater and air conditioner on this
vehicle has the following features:
¥ Interior temperature control.
¥ Air flow control.
¥ Mode (blow port) control.
¥ Intake (switching between fresh air and interior
air) control.
¥ Heater start timing control.
¥ Cooler start timing control.
¥ Evaporator anti-freeze control.
1. Interior Temperature Control
The automatic heater/air conditioner control unit
operates on the setup temperature signal from
the temperature control switch and other sensor
signals to derive the total signal. Then, the
control unit compares this signal against the
signal from the potentiometer to determine
rotation direction of the mix actuator. The mix
actuator moves the air mix door to the aperture
specified by the total signal so that the specified
interior temperature is achieved.
If the compressor is turned off in the A/C (air
conditioning) mode, aperture of the air mix door
is offset according to the outside air temperature
or the specified interior temperature. This
function removes the difference in the blowing
temperature in this state and that of when the
compressor is turned on.
When FH or FC is selected for the setup
temperature, the air mix door is accordingly
fixed to the Full Heat or Full Cool mode.
When the VENT mode is selected, aperture of
the air mix door is controlled so that excessively
heated air may not be blown from the VENT
blow port.
0 50
140 104 68 32
Air mix door aperture
Full cool
Heater
side Restriction on the
aperture enabied
in the VENT modeAir conditioning
ON mode Full heatSet temperature
signal
Mix
actuator
Potentio
meter
Air mix door
In car sensor
Ambient sensor
Sun sensor
Control unitAir conditioning
switch
Set up temperature
signal
Air conditioning
OFF mode
Total signal Cooler
side
C01RY00011

AIR CONDITIONING 1BÐ89
2. Air Flow Control
¥ In the Auto Mode
The automatic heater/air conditioner control unit
operates on the setup temperature signal and
other sensor signals to derive the total signal.
Then, the control unit adjusts base potential of
the power transistor to match it to the voltage
pattern of the target fan so that stage-less fan
speed control can be achieved.
When solar radiation quantity is detected in the
VENT or B/L mode, the control unit increases the
minimum fan voltage to offset.
When FH or FC is selected from the temperature
control switch, air flow is accordingly fixed to
MAX HI or AUTO HI.
¥ In the Manual Mode
Air flow specified from the fan switch is entered
to the automatic heater/air conditioner control
unit as the manual signal. The signal modifies
the air flow to the level specified from the fan
switch so that the required fan voltage is
attained.3. Mode (Blow Port) Control
The automatic heater/air conditioner control unit
operates on the setup temperature from the
control switch, and temperature and solar
radiation quantify from the sensors to determine
the total mode control signal. According to the
pattern specified by this signal, the control unit
selects either one of the VENT, BI-LEVEL, FOOT
or DEF/FOOT mode.
The mode actuator determines the rotation
direction comparing the target position against
the current position being determined by the
position detection signal.
When FH or FC is selected for the temperature
from the temperature control switch, mode is
accordingly fixed to the VENT or FOOT.
¥ In the manual operation of the mode switch, you
can select a desired blow port mode pressing
the corresponding mode switch.
¥ Operating the DEF mode switch selects the DEF
for the blow port mode.
4.512
(V)
M
MAX
HI Relay
Power
transistor
4.8 10.5MAX HI Set up
temperature signal
Control unit
In car sensor
Ambient sensor
Sun sensor
Mode control
signal Fan switch
AUTO HI
Heater
sideCooler
side Total signalVENT mode
Blower fan motor terminal voltage
C01RY00008
Mode control
DEF / FOOTSet up temperature
signal
Mode actuator
Mode doorPosition
detection
switch
Control unit
In car sensor
Sun sensor
Air conditioning
switch
Mode control
signal Ambient sensor
FOOT
BI-LEVEL
VENT
Heater
sideCooler
side Mode total signal
C01RY00009