Isuzu Trooper (2000 year). Service manual - part 39

HEATING, VENTILATION AND AIR CONDITIONING (HVAC) 1A–125

Condition

Possible cause

Correction

The fan dose not rotate at all

—

Refer to Chart A

The fan dose not rotate in the
MAX–HI mode

—

Refer to Chart B

The fan dose not rotate in any mode
other than MAX–HI

—

Refer to Chart C

The fan dose not stop

—

Refer to Chart D

Chart A: Fan Does Not Rotate At All 

Step

Action

Value(s)

Yes

No

1

Are the fuse No.C–19 and No.C–20 normal?

—

Go to Step 2

Replace the

fuse

2

Are the relay No.B–36 and No.I–51 normal?

—

Go to Step 3

Replace the

relay

3

Turn on the ignition switch (the engine is run).

Is the battery voltage applied between the harness side
connector terminal No.B5–1 and ground?

—

Go to Step 5

Go to Step 4

4

Repair an open circuit between terminal No.B5–1 and
No.C–19 fuse.

Is the action complete?

—

Go to Step 3

—

5

Is there continuity between the harness side connector
terminal No.B5–2 and ground (No.B–2)?

—

Go to Step 7

Go to Step 6

6

Repair an open circuit between terminal No.B5–2 and
ground.

Is the action complete?

—

—

—

7

Is the battery voltage applied between the harness side
connector terminal No.B5–2 and No.B5–1?

—

Go to Step 8

Go to Step 9

8

Replace the blower motor.

Is the action complete?

—

Verify repair

—

9

Refer to chart B and C.

Is the action complete?

—

Verify repair

—

1A–126 HEATING, VENTILATION AND AIR CONDITIONING (HVAC)

Chart B: Fan Does Not Rotate in MAX HI Mode 

Step

Action

Value(s)

Yes

No

1

Is the MAX-HI relay (I–51) normal?

—

Go to Step 2

Replace the

relay

2

1. Turn on the ignition switch (the engine is run).
2. Set the fan switch to the MAX-HI.

Is there continuity between the harness side connector
terminal No.B5–2 and No.I51–2?

—

Go to Step 4

Go to Step 3

3

Repair an open circuit between terminal No.B5–2 and
No.I51–2.

Is the action complete?

—

Go to Step 3

—

4

Is there continuity between the harness side connector
terminal No.I51–4 and ground (No.B–2)?

—

Go to Step 6

Go to Step 5

5

Repair an open circuit between terminal No.I51–4 and
ground (No.B–2).

Is the action complete?

—

Go to Step 4

—

6

Is the battery voltage applied between the harness side
connector terminal No.I51–1 and ground?

—

Go to Step 8

Go to Step 7

7

Repair an open circuit between terminal No.I51–1 and
No.C–20 fuse.

Is the action complete?

—

Go to Step 6

—

8

Is the battery voltage applied between the harness side
connector terminal No.I32–12 and ground?

—

Go to Step 10

Go to Step 9

9

Repair an open circuit between terminal No.I51–3 and
No.I32–12.

Is the action complete?

—

Verify repair

—

10

Replace the auto air conditioner control unit.

Is the action complete?

—

Verify repair

—

HEATING, VENTILATION AND AIR CONDITIONING (HVAC) 1A–127

Chart C: Fan Does Not Rotate In Any Mode Other Than MAX HI 

Step

Action

Value(s)

Yes

No

1

Is the power transistor performance normal? (Refer to
the later section on “individual inspection”)

—

Go to Step 2

Replace the

power

transistor

2

Is there continuity between the harness side connector
terminal No.B5–2 and No.I50–1, No.B5–2 and
No.I33–17?

—

Go to Step 4

Go to Step 3

3

Repair an open circuit between terminal.

No.B5–2 and I50–1
No.B5–2 and I33–17

—

Go to Step 2

—

4

Is there continuity between the harness side connector
terminal No.I50–3 and ground (No.B–2)?

—

Go to Step 6

Go to Step 5

5

Repair an open circuit between terminal No.I50–3 and
ground.

Is the action complete?

—

Go to Step 4

—

6

Is there continuity between the harness side connector
terminal No.I50–2 and No.I33–19?

—

Go to Step 8

Go to Step 7

7

Repair an open circuit between terminal No.I50–2 and
No.I33–19.

Is the action complete?

—

Go to Step 6

—

8

Replace the auto air conditioner control unit.

Is the action complete?

—

Verify repair

—

1A–128 HEATING, VENTILATION AND AIR CONDITIONING (HVAC)

Chart D: Fan Does Not Stop 

Step

Action

Value(s)

Yes

No

1

1. Disconnect the max high relay, the power transistor

connector I–50 and the auto A/C control unit
connector I–33.

2. Turn on the ignition switch.

Does the blower motor stop?

—

Go to Step 3

Go to Step 2

2

Repair a short circuit between connector No.B5–2 and
No.I51–2, No.B5–2 and No.I50–1, or No.B5–2 and
I33–17.

Is the action complete?

—

Verify repair

—

3

 Is the max high relay normal? (Refer to the later
section on “individual inspection”.)

—

Go to Step 4

Replace the

relay

4

Reinstall the max high relay.

Does the blower motor start operating?

—

Go to Step 6

Go to Step 5

5

Repair a short circuit between connector No.I51–3 and
No.I32–12.

Is the action complete?

—

Go to Step 4

—

6

Is the power transistor normal? (Refer to the later
section on “individual inspection”.)

—

Go to Step 7

Replace the

power

transistor

7

Reinstall the power transistor.

Does the blower motor start operating?

—

Replace the

auto A/C

control unit

—