Isuzu Trooper (2000 year). Manual — part 31

HEATING, VENTILATION AND AIR CONDITIONING (HVAC) 1A–93

F01RX005

Indication

D

The Auto LED maintains unaffected.

D

Currently selected intake port is indicated.

F01RX007

Fan Switch

1. Sets the fan to the specified mode.
2. Even when the fan switch is turned off, status display

for the Mode, Intake is maintained.

Temperature Control Knob

1. This knob is operable only when the fan is turned on.

It may be used for the MAX control of each block
except the fan.

2. When the manual mode is selected for the fan control,

this manual mode is maintained.

MAX Control

Mix

Fan

Mode

Intake

A/C

MAX/COOL

Full cool

MAX/HI

VENT

REC*1

ON mode*2

MAX/HEAT

Full hot

AUTO/HI

FOOT*3

FRESH

Current status is

maintained

*1: In the A/C: OFF mode, FRESH shall be selected.
*2: The ON mode is available only when ON is selected

for the fan as well as for the cold outside air
ON/OFF selection.

*3: When the MAX control is selected from the DEF

mode, this DEF mode shall be maintained.

1A–94 HEATING, VENTILATION AND AIR CONDITIONING (HVAC)

Indication

D

As long as the MAX control is selected, the
immediately preceding indication shall be maintained
for the AUTO.

D

Status display is provided for others.

Air Conditioning Switch

Pressing this switch turns on or off the A/C (air
conditioning) control. (The compressor remains turned
off if the fan is turned off and also the compressor has
been turned off because of the given outside air
temperature level.)

Indication

1. The A/C LED remains turned on even if the

compressor has been turned off because of the given
outside air temperature level. In this case, however,
the AUTO or DEF switch must be turned on and the
A/C ON mode must also be turned on (by the MAX/C
mode).

2. Pressing the A/C switch from the above state (1)

turns off the A/C LED.

Overview of Construction, Movement
and Control of Major Parts of
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.

865RY00020

Legend

(1) In Car Sensor
(2) Automatic Air Conditioner Control Unit

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
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.

845RY00001

Legend

(1) Ambient Sensor
(2) Condenser Assembly

HEATING, VENTILATION AND AIR CONDITIONING (HVAC) 1A–95

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 “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.

860RY00007

Legend

(1) Duct Sensor
(2) Electro Thermo
(3) Evaporator

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 heater/air
conditioner control unit.
This sensor is provided at top of the defroster grill.

826RY00012

Legend

(1) Sun Sensor

Power Transistor

Receiving base current from the automatic heater/air
conditioner control unit, the power transistor implements
stage–less speed change of the blower fan motor. This
transistor is provided on the evaporator.

874RY00011

Legend

(1) Evaporator Assembly
(2) Power Transistor

1A–96 HEATING, VENTILATION AND AIR CONDITIONING (HVAC)

Max Hi Relay

This relay turned on or off by the signal from the automatic
heater/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

Actuator

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)
and the cold air bypassing actuator.

860RY00006

Legend

(1) Mix Actuator
(2) Intake Actuator
(3) Blower Unit
(4) Mode Actuator
(5) Heater Unit