Isuzu Amigo / Axiom / Trooper / Rodeo / VehiCross. Manual - part 558

1A–100 HEATING, VENTILATION AND AIR CONDITIONING (HVAC)

Intake (Fresh air/interior air switching)
Control

In the Full Auto mode, the automatic air conditioner
control unit operates on the setup temperature signal and
other sensor input signals to derive the total signal.
According to the pattern specified by this signal, the
control unit provides the intake control.
When the fan is turned off or the A/C (air conditioning) is
turned off, the intake is fixed to the FRESH mode.
When FC or FH is selected from the control switch, the
intake mode is accordingly fixed to the RECIRC or
FRESH.

In the Manual Operation

Pressing the FRESH (fresh air intake) or the RECIRC
(room air circulation) accordingly selects the FRESH
or RECIRC mode.

When the DEF Mode Switch is depressed

The intake mode is fixed to the FRESH. When the
MANU REC is selected, however, the mode is fixed
the RECIRC.

When the Mode Switch is depressed

If the automatic intake control is selected, the intake is
fixed to the currently selected mode.

C01RY00012

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
duct sensor. And, when outside air is detected to be low
through the ambient 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.

C01R200019

Heating Start Timing Control

When the automatic air conditioner is started, heating is
turned on under following conditions.

The detected temperature of thermo unit is 58

(136

F) or less.

The temperature setting signal and the total signal by
each sensor meet the condition of heating.

When the detected temperature by the coolant
temperature sensor is 58

C (136

F) or less, the blower

fan motor is set to work at low speed and the “DEF” mode
is selected.
When the detected temperature by the coolant
temperature sensor is 25

C (77

F) or more, the blow

mode changes automatic control. And the blower fan
speed is controlled to be lineally up from “LO” to “MAX HI”.

HEATING, VENTILATION AND AIR CONDITIONING (HVAC) 1A–101

840R200012

Cooling Start Timing Control

When the automatic air conditioner is started, cooling is
turned on under following conditions.

The in car sensor is 30

C (86

F) or more.

The temperature setting signal and the signals from
each sensor meet the specified condition.

The blower fan speed is set to “LO” for maximum 7
seconds when cooling start conditions meet, and then, is
controlled to be lineally up to “MAX HI” by 5.32%/S.

C06RY00001

1A–102 HEATING, VENTILATION AND AIR CONDITIONING (HVAC)

Troubleshooting

Troubleshooting, Its Overview and
Procedures

The full automatic heater and air conditioner equips with
the “Self-Diagnosis Function” 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 “Checking Procedures by Failed
Location”. As for a location this function is unappreciable,
the system accurately determines characteristics of a
given trouble and checks relevant parts according to the
“Checking Procedures by Failed Location”.
The following illustrates basic troubleshooting flow.

Basic Troubleshooting Flow

F01RX009

HEATING, VENTILATION AND AIR CONDITIONING (HVAC) 1A–103

Auto Air Conditioner Control Unit Power Supply Diagnosis

This check is required because a trouble on the auto
amplifier (control unit) power supply circuit or grounding
circuit prevents accurate troubleshooting.

D08R200263

Condition

Possible cause

Correction

Power source does not supply to
auto air conditioner control unit.

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Refer to Chart A

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