sensor ISUZU AXIOM 2002 Service Owner's Manual

1A±84
HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
Mode (Blow Port) Control
The A/C control unit receives temperature setting data as
well as temperature and solar radiation level data from the
various sensors. Based on this data, the control unit
compiles a composite TMO signal. The TMO signal
allows the outlet positions to be changed in a set pattern
(VENT"BI-LEVEL"FOOT"DEFROST/FOOT).
The mode actuator acts in response to mode position. It
compares data signals received from the target mode, the
door position, and mode door position to determine the
direction of rotation.
If the temperature is set to 18
C (65
F), cool air is
discharged from the head outlets. If t he temperature is
set to 32
C (90
F), warm air is discharged from the foot
outlets.
In manual mode, existing air outlet settings remain
unchanged when the temperature is set to 18
C (65
F) or
32
C (90
F).

Press the mode switch to change to the outlet mode.
Blower operation (outlet mode position) can now be
switched between the VENT, BI-LEVEL, FOOT, and DEF
positions.

The DEF position can be selected from the outlet mode.
C01R200003
Intake (Fresh air/interior air switching)
Control
During automatic operation, the A/C control unit responds
to the temperature setting signal together with signals
from the various sensors to generate a general signal that
controls operation in a prescribed pattern.
If either or both the fan and the cooler are off, air intake is
from outside the vehicle.
If the temperature control switch is set to either 18
C
(65
F) or 32
C (90
F), the air inside the vehicle is
recirculated.
1. Manual switch operation
Press the intake switch to change between outside air
intake and recirculated inside air.
2. Defrost switch operation
Air intake is from outside the vehicle.
3. Mode switch operation
During automatic operation, outside air intake or
recirculated inside air is selected as appropriate.
During manual operation or when the DEF mode is
selected, air intake is from outside the vehicle.
C01R200004

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
1A±85
Compressor Control
In the automatic control mode, the automatic air
conditioner control unit turns on or off the compressor
with the evaporator anti-freeze mechanism using the
evaporation sensor. And, when outside air is detected to
be low through the outside air temperature sensor signal,
the control unit turns off the compressor using the
compressor control function.
Manual Control

In the automatic control mode, pressing the A/C (air
conditioning) switch turns off the compressor.

Pressing the DEF mode switch automatically turns on
the compressor.
C01R200002
Heater Start-up Control
Heater start-up control occurs when the air discharge
mode is in the BI=LEVEL, FOOT, or DEF/FOOT position
and the heater core temperature is less than 14
C (58
F).
Air discharge volume remains in the AUTO LO mode until
the engine coolant temperature rises above 14
C (58
F).
The volume then increases in linear increments to the
pre-set level.
840R200010
Cooler Start-up Control
When cooler operation is started with the air discharge
mode is in the VENT or B/L position and the in-car
temperature higher than 26
C (78
F) (detected by the
in-car sensor), cooler start-up control occurs.
For the first 7 seconds of cooler operation, the fan
remains OFF. It then switches to AUTO LO. Air discharge
volume then increases in linear increments to the pre-set
level.
Cooler start-up control occurs the first time the engine is
started or the cooler switch is moved from OFF to AUTO.
It will not occur during subsequent switch movements.
C06R200001

1A±86
HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
Troubleshooting
Troubleshooting, Its Overview and
Procedures
The automatic air conditioner equips with the
ªSelf-Diagnosis Functionº to check its major components.
This function makes access to the sensors, actuators and
blower fan motor system easier when checking them up
and, when a failed part is located, this function restores its
original performance.When implementing the troubleshooting, this
self-diagnosis function narrows the range to be searched
at the first step, then check relevant parts one by one
according to the ªChecking Procedures by Failed
Locationº. As for a location this function is unappreciable,
the system accurately determines characteristics of a
given trouble and checks relevant parts according to the
ªChecking Procedures by Failed Locationº.
The following illustrates basic troubleshooting flow.
Basic Troubleshooting Flow
F01RX009

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
1A±91
Troubleshooting With Self-Diagnosis Function
Overview of Self-Diagnosis Function
Sensors (input) and actuators (output) are used to check
circuit function and provide essential data on these
circuits. For more detailed information, refer to the
[Inspection and Repair] Sections for the applicable
system or component.
The Table below shows how to turn the self-diagnosis
function on and off.
Self-Diagnosis Operation Procedure
865R200033

1A±92
HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
StepActionValue(s)Ye sNo
11. Allow the engine to idle until it completely warms up.
2. Turn the starter switch to the OFF position.
3. Place a 60±watt lamp approximately 15 cm from the
sun sensor.
NOTE: This procedure is best performed at night or in
a dark, unlit area.
Is the action complete?
ÐGo to Step 2Ð
2Simultaneously press and hold the RESET key and the
CLOCK key (display unit).
Move the starter switch to start the engine.
Does DIAG appear on the display?
ÐGo to Step 3
Replace
display unit
3Press the COMPUTER MODE key.
Does DIAG AIRCON appear on the display?
ÐGo to Step 4
Replace
audio unit
4NOTE: A '1' should appear in the set temperature
segment of the display.
Does '0' appear in the outside air segment of the
display?
ÐGo to Step 6Go to Step 5
5Repair or replace damaged parts.
NOTE: Refer to
Step 1 Trouble Code Table.
Is the action complete?ÐGo to Step 1Ð
6Press and release the  fan switch (one time only).
NOTE: A '2' should appear in the set temperature
segment of the display.
Does '0' appear in the outside air segment of the
display?
ÐGo to Step 8Go to Step 7
7Repair or replace damaged parts.
NOTE: Refer to
Step 2 Trouble Code Table.
Is the action complete?ÐGo to Step 1Ð
8Press and release the  fan switch (one time only).
NOTE:

Refer to
Step 3 Sensor Output Check for a sample
output value.

A '3' should appear in the set temperature
segment of the display.
Does the correct sensor output value appear in the
outside air segment of the display?
ÐGo to Step 10Go to Step 9
9Repair or replace damaged parts.
NOTE: Refer to
Trouble Spot Inspection.
Is the action complete?ÐGo to Step 1Ð
10Press and release the  fan switch one time only.
NOTE: Refer to
Step 4 (Operation Check) for display
readings and inspection steps.
Are all parts operating normally?
ÐGo to Step 12Go to Step 11

1A±94
HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
STEP 1: Trouble Code Table
Trouble
CodeDefective PartTrouble
CodeDefective Part
1In Car Sensor Open Circuit± 1In Car Sensor Short Circuit
2Ambient Sensor Open Circuit± 2Ambient Sensor Short Circuit
3Sun Sensor Open Circuit± 3Sun Sensor Short Circuit
4Duct Sensor Open Circuit± 4Duct Sensor Short Circuit
5Mix Potentiometer Open Circuit± 5Mix Potentiometer Short Circuit
6Mode Encoder Open Circuit
7Intake Encoder Open Circuit
0No Defective Part
STEP 2: Trouble Code Table
Trouble
CodeDefective PartTrouble
CodeDefective Part
1In Car Sensor Open Circuit± 1In Car Sensor Short Circuit
2Ambient Sensor Open Circuit± 2Ambient Sensor Short Circuit
3Not Used± 3Sun Sensor Short Circuit
4Duct Sensor Open Circuit± 4Duct Sensor Short Circuit
5Mix Potentiometer Open Circuit± 5Mix Potentiometer Short Circuit
6Mode Encoder Open Circuit
7Intake Encoder Open Circuit
0No Defective Part

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
1A±95
STEP 3: Sensor Output Check
865R200035

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
1A±97
Inspection By Failed Location
Inspection of the Sensors
When the self-diagnosis function has determined that
trouble is present on the sensors, check them according
to the following flow chart.
F01RY00005

1A±98
HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
Chart 1: In Car Sensor
D08R200029
StepActionValue(s)Ye sNo
1Disconnect the in car sensor connector. (No.I-17)
Is performance of the sensor normal? (Refer to the
later section on ªIndividual Inspectionº)ÐGo to Step 2
Replace the
in car sensor
2Is there continuity between the harness side connector
No.I20±1 and No.I17±3?
ÐGo to Step 4Go to Step 3
3Repair an open circuit between terminal No.I20±1 and
No.I17±3.
Is the action complete?
ÐGo to Step 2Ð
4Is there continuity between the harness side connector
No.I20±11 and No.I17±4?
ÐGo to Step 6Go to Step 5
5Repair an open circuit between terminal No.I20±11 and
No.I17±4.
Is the action complete?
ÐGo to Step 4Ð
6Replace the auto air conditioner control unit.
Is the action complete?
ÐVerify repairÐ

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
1A±99
Chart 2: Ambient Sensor
D08R200030
StepActionValue(s)Ye sNo
1Disconnect ambient sensor connector. (No.C±19)
Is performance of the ambient sensor normal? (Refer
to the
later section on ªIndividual inspectionº)ÐGo to Step 2
Replace the
ambient
sensor
2Connect the ambient sensor connector.
Is resistance between the harness side connector
No.I20±2 and No.I20±11 normal?Refer to the
later section
on ªIndividual
inspectionº
Go to Step 4Go to Step 3
3Repair an open circuit between terminal No.I20±2 and
No.C19±1 or No.I20±11 and No.C19±2.
Is the action complete?
ÐVerify repairÐ
4Replace the auto air conditioner control unit.
Is the action complete?
ÐVerify repairÐ