sensor ISUZU AXIOM 2002 Service User Guide

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
1A±45
Evaporator Assembly
Evaporator Assembly and Associated Parts
874R200015
Legend
(1) Refrigerant Line
(2) Drain Hose
(3) Dash Side Trim Panel
(4) Power Transistor and Duct Sensor Connector(5) Passenger Lower Bracket
(6) Sill Plate
(7) Evaporator Assembly
(8) Glove Box
Removal
1. Disconnect the battery ground cable.
2. Discharge and recover refrigerant.

Refer to
Refrigerant Recovery in this section.
3. Remove glove box.
4. Disconnect power transistor (2) and duct sensor
connector (1).
5. Remove sill plate.
6. Remove dash side trim panel.
7. Remove passenger lower bracket.
8. Disconnect drain hose.
874R200005

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
1A±47
Duct Sensor, Evaporator Core and/or Expansion Valve
Disassembled View
874R200012
Legend
(1) Lining
(2) Expansion Valve
(3) O-ring
(4) Evaporator Assembly
(5) Lower Case(6) Clip
(7) Attaching Screw
(8) Evaporator Core
(9) Duct Sensor
(10) Upper Case
Removal
1. Disconnect the battery ground cable.
2. Discharge and recover refrigerant.

Refer to
Refrigerant Recovery in this section.
3. Remove evaporator assembly.

Refer to
Evaporator Assembly in this section.
4. Remove the duct sensor fixing clip.
Pull the sensor from the evaporator assembly.
5. Remove clip.
6. Remove attaching screw.
7. Remove upper case.
8. Remove lower case.

Slit the case parting face with a knife since the lining
is separated when removing the evaporator.
874RS006

1A±48
HEATING, VENTILATION AND AIR CONDITIONING (HVAC)

Lift to remove the upper case.
874R200007
9. Remove evaporator core.
874R200008
10. Remove expansion valve.

Tear off the insulator carefully.

Remove the sensor fixing clip.

Use a back-up wrench when disconnecting all
refrigerant pipes.
Installation
To install, follow the removal steps in the reverse order,
noting the following points:
1. The sensor is installed on the core with the clip.
2. The sensor must not interfere with the evaporator
core.
3. When installing the new evaporator core, install the
duct sensor (2) to the evaporator core (1) specified
position with the clip in the illustration.
874RY00016
4. O-rings cannot be reused. Always replace with new
ones.
5. Be sure to apply new compressor oil to the O-rings
when connecting lines.
6. Be sure to install the sensor and the insulator on the
place where they were before.
7. To install a new evaporator core, add 50cc (1.7 fl. oz.)
of new compressor oil to the new core.
8. Tighten the refrigerant lines to the specified torque.
Refer to
Main Data and Specifications for Torque
Specifications in this section.
9. Apply an adhesive to the parting face of the lining
when assembling the evaporator assembly.

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
1A±53
Compressor
Service Precaution
WARNING: THIS VEHICLE HAS A SUPPLEMENTAL
RESTRAINT SYSTEM (SRS). REFER TO THE SRS
COMPONENT LOCATION VIEW IN ORDER TO
DETERMINE WHETHER YOU ARE PERFORMING
SERVICE ON OR NEAR THE SRS COMPONENTS OR
THE SRS WIRING. WHEN YOU ARE PERFORMING
SERVICE ON OR NEAR THE SRS COMPONENTS OR
THE SRS WIRING, REFER TO THE SRS ON-VEHICLE
SERVICE INFORMATION. FAILURE TO FOLLOW
CAUTIONS COULD RESULT IN POSSIBLE AIR BAG
DEPLOYMENT, PERSONAL INJURY, OR
OTHERWISE UNNEEDED SRS SYSTEM REPAIRS.
CAUTION: Always use the correct fastener in the
proper location. When you replace a fastener, use
ONLY the exact part number for that application.
ISUZU will call out those fasteners that require a
replacement after removal. ISUZU will also call out
the fasteners that require thread lockers or thread
sealant. UNLESS OTHERWISE SPECIFIED, do not
use supplemental coatings (paints, greases, or other
corrosion inhibitors) on threaded fasteners or
fastener joint interfaces. Generally, such coatings
adversely affect the fastener torque and the joint
clamping force, and may damage the fastener. When
you install fasteners, use the correct tightening
sequence and specifications. Following these
instructions can help you avoid damage to parts and
systems.
General Description
When servicing the compressor, keep dirt or foreign
material from getting on or into the compressor parts and
system. Clean tools and a clean work area are important
for proper service. The compressor connections and the
outside of the compressor should be cleaned before any
ºOn±Vehicleº repair, or before removal of the
compressor. The parts must be kept clean at all times and
any parts to be reassembled should be cleaned with
Trichloroethane, naphtha, kerosene, or equivalent
solvent, and dried with dry air. Use only lint free cloths to
wipe parts.
The operations described below are based on bench
overhaul with compressor removed from the vehicle,
except as noted. They have been prepared in order of
accessibility of the components. When the compressor is
removed from the vehicle for servicing, the oil remaining
in the compressor should be discarded and new
compressor oil added to the compressor.
Compressor malfunction will appear in one of four ways:
noise, seizure, leakage or low discharge pressure.
Resonant compressor noises are not cause for alarm;
however, irregular noise or rattles may indicate broken
parts or excessive clearances due to wear. To check
seizure, de±energize the magnetic clutch and check tosee if the drive plate can be rotated. If rotation is
impossible, the compressor is seized. Low discharge
pressure may be due to a faulty internal seal of the
compressor, or a restriction in the compressor. Low
discharge pressure may also be due to an insufficient
refrigerant charge or a restriction elsewhere in the
system. These possibilities should be checked prior to
servicing the compressor. If the compressor is
inoperative, but is not seized, check to see if current is
being supplied to the magnetic clutch coil terminals.
The compressor oil used in the HFC±134a system
compressor differs from that used in R±12 systems.
Also, compressor oil to be used varies according to the
compressor model. Be sure to avoid mixing two or more
different types of oil.
If the wrong oil is used, lubrication will be poor and the
compressor will seize or malfunction.
DKV-14G Type Compressor
DKV±14G is equipped with five±vane rotary compressor.
These vanes are built into a rotor which is mounted on a
shaft.
When the shaft rotates, the vanes built into the cylinder
block assembly are operated by centrifugal force.
This changes the volume of the spare formed by the rotor
and cylinder, resulting in the intake and compression of
the refrigerant gas. The discharge valve and the valve
stopper, which protects the discharge valve, are built into
the cylinder block assembly. There is no suction valve but
a shaft seal is installed between the shaft and head; a
trigger valve, which applies back pressure to the vanes, is
installed in the cylinder block and a refrigerant gas
temperature sensor is installed in the front head.
The specified quantity of compressor oil is contained in
the compressor to lubricate the various parts using the
refrigerant gas discharge pressure.
871RX002

1A±64
HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
Automatic Air Conditioning System
General Description
Using a variety of sensors, this automatic air conditioner
accurately senses outside air temperature, solar
radiation quantity, evaporator's blowing temperature, and
interior temperature, then enters these data to the
automatic air conditioner control unit (equipped with the
built-in micro-computer). The data provided to the control
unit enables to automatically control blow temperatureand blow air quantity, turn on or off the compressor and
switch the blow port as well as switching between the
fresh air intake and interior air circulation.
Resetting the automatic function allows you to switch to
the manual control mode.
The self-diagnoisis function of the automatic air
conditioner control unit (with the built-in micro-computer)
allows the unit to access and diagnose a failed part easier
and quicker.
Automatic Air Conditioner Parts Configuration
865R200050
Legend
(1) In Car Sensor
(2) Sun Sensor
(3) Ambient Sensor
(4) Intake Actuator
(5) Blower Unit
(6) Max ± High Relay
(7) Display(8) Audio & Switch Assembly
(9) Evaporator Assembly
(10) Duct Sensor
(11) Mix Actuator
(12) Heater Unit
(13) Automatic Air Conditioner Control Unit
(14) Mode Actuator

1A±70
HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
Functions and Features
Automatic air conditioning control unit
The control unit features a prominent control and display
panel that clearly shows air conditioner operational
settings (delivered air volume, air outlet location,
inside/outside air circulation, and set temperature).
Desired temperature can be set in ±17
C (1
F)
increments. The current setting appears on the digital
display.
Automatic temperature control
Vehicle interior temperature is maintained at the set level.
It is unaffected by changes in vehicle speed, outside air
temperature, and number of passengers.
Maximum cooling and heating
Moving the switch to the 18
C (65
F) position provides
maximum cooling. Moving the switch to the 32
C (90
F)
position provides maximum heating.
Automatic air flow control
Air flow is automatically and precisely regulated in
response to set temperature change and/or changes in
heater unit mixing door aperture.
Automatic air outlet selection
Appropriate air outlets (VENT, BE-LEVEL, FOOT, or
DEF) are selected in response to changes in outlet
temperatures. The mode switch permits manual selection
of the desired air outlet.
Air source (Fresh air intake from outside the
vehicle or recirculation of the air inside the vehicle)
selection
Automatic switching between outside air (FRESH),
recirculated inside air (RECIRC), or a combination of the
two (MIX) occurs in response to changes in outlet
temperatures.The intake switch permits manual
selection of the air source (FRESH or RECIRC). Mixing
of the two sources is not possible during manual
operation. When the defrost mode switch (DEF) is
pressed, the system automatically switches to outside air
intake.
Cooler start-up control
When the vehicle is parked in a hot area for an extended
period of time, the evaporator becomes hot. When the
cooler is turned on, hot air is blown into the vehicle until
the evaporator cools down. The cooler start-up control
prevents blower operation until the evaporator is able to
provide cool air.
Heater start-up control
When the vehicle is parked in a cold area for an extended
period of time, the heater core becomes cold. When the
heater is turned on, cold air is blown into the vehicle until
the heater core heats up. The heater start-up control
prevents blower operation to the air outlets until the
heater core is able to provide warm air. Air is delivered
through the defrost outlets.
Solar radiation offset
The sun sensor uses a photodiode to precisely determine
the amount of solar radiation affecting the vehicle. The
cooler operates in response to this radiation to quickly
correct the vehicle interior temperature.Switch position memory
Current switch positions are stored in memory when the
ignition switch is turned off. When the ignition switch is
turned on again, the switches automatically return to the
position they were in when the ignition switch was turned
off. This simplifies the restarting procedure.
Self-diagnosis function
The self-diagnosis switches on the control panel permit
easy system troubleshooting. Refer to ªSelf-Diagnosisº
later in this Section.

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
1A±77
Overview of Construction, Movement
and Control of Major Parts of
Automatic Air Conditioner System
Automatic 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 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 right side of meter cluster.
865R200001
Legend
(1) Meter Cluster
(2) In Car Sensor
Ambient 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
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.
875R200017
Legend
(1) Ambient Sensor
(2) Condenser Assembly
Duct Sensor
The duct sensor is the sensor to detect temperature
change of the side of evaporator blower coming by fresh
recirculation of intake door or ªonº ªoffº 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.
874R200001
Legend
(1) Sensor Part
(2) Duct Sensor Assembly
(3) Evaporator Assembly

1A±78
HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
Sun 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 air
conditioner control unit.
This sensor is provided at top of the center cluster upper.
865R200002
Legend
(1) Sun Sensor
(2) Center Cluster Upper
Power Transistor
Receiving base current from the automatic air conditioner
control unit, the power transistor implements stage-less
speed change of the blower fan motor. This transistor is
provided on the evaporator.
874R200009
Legend
(1) Evaporator Assembly
(2) Power Transistor
Max Hi Relay
This relay turned on or off by the signal from the automatic
air conditioner control unit. As the Max Hi relay is turned
on, supply voltage is directly fed to the blower fan motor to
select the Max Hi mode.
873RY00005
Legend
(1) Blower Unit
(2) Max High Relay

1A±82
HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
Automatic Air Conditioning System
System Overview (Chart)
Conditions both inside and outside the vehicle are
detected by sensors (in-car temperature sensor, ambient
temperature sensor, duct sensor, sun sensor, speed
sensor, and water temperature sensor). These sensors
send signals to the control unit.
Potentiometer position sensors send data to the control
unit. Signals related to control panel settings are also sent
to the control unit.In response to the signals received, the control unit
automatically adjusts air-mix door aperture (outlet air
temperature), fan speed (forced air volume), and air
intake (outside air, recirculated inside air, or a mixture of
the two).
F01R200003

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
1A±83
Interior Temperature Control
When the temperature control switch is set to a specific
temperature, a signal is sent to the A/C control unit. Other
signals are sent to the control unit from the various
sensors. This data is analyzed by the control unit which
creates a composite data signal that is compared with the
signal received from the potentiometer. The result
determines the direction of mix actuator rotation.
The mix actuator reacts to the composite air mix door
opening angle signal. Opening angle is increased or
decreased to maintain the temperature at the selected
level.
When the compressor is off, the air mix door moves
toward the COOL side. When the compressor turns on,
the temperature of the air being discharged from the
outlet vents is regulated.
When the temperature control is set to 18
C (65
F), the
air mix door moves to the FULL COOL position. When the
control is set to 32
C (90
F), the door moves to the FULL
HOT position.
In the VENT position, the air mix door moves from FULL
COOL to a 60% aperture. This prevents hot air from being
discharged into the vehicle.
C01R200005
Air Flow Control
In the Auto Mode

Automatic operation
When the AUTO switch or the DEF switch is pressed, a
signal indicating the forced air volume is sent to the A/C
auto-control unit. Other signals are sent to the control
unit from the various sensors. This data is analyzed by
the control unit which creates a composite data signal.
Based on this signal, the base voltage of the power
transistor is varied to change the blower voltage. This
results in a non-stepped change in blower motor
speed.
When the temperature control switch is set to either
18
C (65
F) or 32
C (90
F), blower motor speed is in
the MAX-HI mode.
In the Manual Mode

Manual operation
When the fan switch is manually set to a specified air
volume, a signal is sent to the A/C auto-control-unit. In
response to this signal, the auto-control unit controls
the blower voltage.
When the fan switch is set to HI, the max-hi relay
operates to increase blower motor speed to the
MAX-HI mode.
C01R200001