Isuzu Amigo / Axiom / Trooper / Rodeo / VehiCross. Manual - part 535

1A–8

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)

Wiring Diagram

D01R200019

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)

1A–9

Diagnosis

Heating Cycle diagnosis

Condition

Possible cause

Correction

No heating or insufficient heating.

Blower motor does not run or runs
improperly.

Refer to “FAN CONTROL LEVER
(FAN SWITCH) DIAGNOSIS”.

Engine coolant temperature is low.

Check the engine coolant
temperature after warming up the
engine and check the thermostat.
Replace as necessary.

Insufficient engine coolant.

Add engine coolant as required.

Circulation volume of engine coolant
is insufficient.

Check if the water hose to the heater
core is clogged, collapsed or twisted.
Repair or replace as necessary.

Heater core clogged or collapsed.

Clean or replace as necessary.

The heater cores is not provided with
air sent from the blower motor.

Repair the temperature control link
unit or mode doors.

Duct connections defective or
unsealing.

Repair or replace as necessary.

Control lever moves but mode door

Cable attaching clip is not correct.

Repair

does not operate.

Link unit of heater or blower
assembly defective.

Repair

The mode door cannot be set to the
mode selected.

Link unit of heater unit or blower
assembly defective.

Repair.

Control cable is not adjusted.

Adjust.

1A–10 HEATING, VENTILATION AND AIR CONDITIONING (HVAC)

Fan Control Lever (Fan Switch) Diagnosis

Current flows to the blower motor through the heater and
the A/C relay (B-36) to activate the rotation of the blower
motor by turning “ON” the fan control knob (fan switch).
Blower motor speed is controlled in stages by the resistor,
by operating the switch from “LOW” to “HIGH”.
For the inspection of the relays, switches and units in
each table, refer to “INDIVIDUAL INSPECTION” in this
section.

D01R200020

Condition

Possible cause

Correction

Blower motor does not run.

—

Refer to Chart A

Blower motor does not run in certain
position (s).

—

Refer to Chart B, C, D and E

Blower motor does not stop at “OFF”
position.

—

Refer to Chart F

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)

1A–11

Chart “A” Blower Motor Dose Not Run 

Step

Action

Yes

No

1

Is relay (B-36) OK?

Go to Step 2

Replace

2

Is fuse C-19 (25A) OK?

Go to Step 3

Replace

3

Is resistor OK?

Go to Step 4

Replace

4

Is fan control knob OK?

Go to Step 5

Replace control

lever assembly.

5

Is blower motor OK?

Go to Step 6

Replace

6

1. Turn the ignition switch “ON”.
2. Turn fan control knob “ON”.
3. Check to see if battery voltage is present at chassis side

connector terminal No. B5-1

Is there a battery voltage?

Poor ground or

open circuit either

between chassis

side connector

terminal No. B5-2

and No. I41-2 or

No. I18-1 and

body ground (No.

B-2).

Open circuit

between No.

C-19 (25A) fuse

and No. B5-1.

Chart “B” Blower Motor Does Not Run At Low Position 

Step

Action

Yes

No

1

Is resistor OK?

Go to Step 2

Replace

2

Is fan control knob (Fan Switch) OK?

Open circuit

between chassis

side connector

terminal No. I41-1

and No.I18-2.

Replace control

lever assembly.

Chart “C” Blower Motor Dose Not Run At Medium Low Position 

Step

Action

Yes

No

1

Is resistor OK?

Go to Step 2

Replace

2

Is fan control knob (Fan Switch) OK?

Open circuit

between the
chassis side

connector

terminal No. I41-4

and No. I18-5.

Replace control

lever assembly.

Chart “D” Blower Motor Dose Not Run At Medium High Position 

Step

Action

Yes

No

1

Is resistor OK?

Go to Step 2

Replace

2

Is fan control knob (Fan Switch) OK?

Open circuit

between chassis

side connector

terminal No. I41-6

and No. I18-3.

Replace control

lever assembly.