Isuzu Amigo / Axiom / Trooper / Rodeo / VehiCross. Service manual — part 8

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)

1A–3

Service Precaution

WARNING: THIS VEHICLE HAS A SUPPLEMENTAL
RESTRAINT SYSTEM (SRS). REFER TO THE SRS
COMPONENT AND WIRING 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 SERVICE INFORMATION. FAILURE TO
FOLLOW WARNINGS 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.

Heating and Ventilation System

General Description

Heater

When the engine is warming up, the warmed engine
coolant is sent into the heater core. The heater system
supplies warm air into the passenger compartment to
warm it up.
Outside air is circulated through the heater core of the
heater unit and then into the passenger compartment. By
controlling the mixture of outside air and heater core air,
the most comfortable passenger compartment
temperature can be selected and maintained.
The temperature of warm air sent to the passenger
compartment is controlled by the temperature control
knob. This knob acts to open and close the air mix door,
thus controlling the amount of air passed through the
heater core.

The air selector switch (Mode SW), with its different
modes, also allows you to select and maintain the most
comfortable passenger compartment temperature.
The air source select switch is used to select either
“FRESH” for the introduction of the outside air, or “CIRC”
for the circulation of the inside air. When the switch is set
to “FRESH”, the outside air is always taken into the
passenger compartment. When setting the switch to
“CIRC” position, the circulation of air is restricted only to
the inside air with no introduction of the outside air and the
air in the passenger compartment gets warm quickly.
However, the switch is normally set to “FRESH” to
prevent the windshield from clouding.

1A–4

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)

840R200007

Legend

(1) Defroster Nozzle
(2) Ventilation Duct
(3) Blower Assembly

(4) Evaporator Assembly
(5) Ventilation Lower Duct
(6) Heater Unit
(7) Rear Heater Duct

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)

1A–5

C01RW001

Air Source Select Switch

Press this button to select either Fresh Air Intake or CIRC
(inside air circulation). There is an indicator light inside the
button. This light indicates that the CIRC mode is “ON”.
Fresh Air Intake is the default setting for both DEFROST
and FOOT/DEFROST.

Fan Control Switch

This switch controls the blower motor speed to regulate
the amount of air delivered to the defrost, foot, and
ventilation ducts:

1. L0
2. M1
3. M2
4. M3
5. HI

Temperature Control Switch

When the temperature control switch is in the “18

°

C

(65

°

F)” position, the air mix door closes to block the air

flow to the heater core.
When the temperature control switch is in the “32

°

C

(90

°

F)” position, the air mix door opens to allow air to pass

through the heater core and heat the passenger
compartment.
Selecting the desired temperature will control the air flow
through the heater core, allowing control of the cabin
temperature.

1A–6

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)

Heater Unit

Heater Unit and Associated Parts

840R200008

Legend

(1) Instrument Panel Assembly
(2) Cross Beam Assembly
(3) Instrument Panel Bracket W/Suspension

Control Unit

(4) Ventilation Lower Duct

(5) Rear Heater Duct
(6) Evaporator Assembly
(7) Heater Unit Assembly
(8) Heater Hose
(9) Power Transistor Connector

Removal

1. Disconnect the battery ground cable.
2. Drain the engine coolant.
3. Discharge and recover refrigerant (with air

conditioning).

D

Refer to

Refrigerant Recovery in this section.

4. Remove the Instrument panel assembly.

D

Refer to

Instrument Panel Assembly in Body and

Accessories section.

5. Remove instrument panel bracket w/suspension

control unit.

D

Refer to

Cross Beam Assembly in Body and

Accessories section.

6. Cross Beam Assembly.

D

Refer to

Cross Beam Assembly in Body and

Accessories section.

7. Disconnect power transistor connector.
8. Remove evaporator assembly.

D

Refer to

Evaporator Assembly in this section.

9. Remove ventilation lower duct.

10. Remove rear heater duct.

D

Remove foot rest, carpet and 3 clips.

11. Disconnect mode/mix actuator connector.

12. Remove heater unit assembly.

D

Disconnect heater hoses at heater unit.

Installation

To install, follow the removal steps in the reverse order,
noting the following points:

1. When handling the PCM and the control unit, be

careful not to make any improper connection of the
connectors.