switch ISUZU TF SERIES 2004 Workshop Manual

1-78 HEATER AND AIR CONDITIONING


RTW4A0SH000201

Pressure switch
Disconnect pressure switch connector and check for continuity
between pressure switch side connector terminal.


825r300045


Heater and thermo switch relay.
Check for continuity between the relay terminals.

1 - 5





No continuity
(When battery voltage is applied between 2 - 4 )
1 - 5





Continuity
825r300023

Check for continuity between the relay terminals.
1 - 2





No continuity
(When battery voltage is applied between 3 - 4 )
1 - 2





Continuity

HEATER AND AIR CONDITIONING 1-79

TROUBLESHOOTING
FAN CONTROL KNOB (FAN SWITCH)
Current flows to the blower motor through the Heater & A/C relay (X-11) 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.”

D08R300046-X2

1-80 HEATER AND AIR CONDITIONING

BLOWER MOTOR DOES NOT RUN


Replace
YES

Is No.SBF-8 (30A) slow blow fuse OK?

Is heater & A/C relay (X-11) OK?
YES

Is resistor OK?
YES

Is fan control knob (Fan switch) OK?
YES
YES

Check to see if battery voltage is present at
chassis side connector terminal No.C105-1 is there a
battery voltage?

Turn the ignition switch "ON" (Engine is running)

Fan control knob (Fan switch) "ON"

Is blower motor OK?
YES
Poor ground or open circuit either between chassis
side connector terminal No.C105-2 and No.C104-3
or No.B13-1 and body ground No.C-109.
NO
Replace
NO
Replace
NO
NO
Replace control lever
assembly
Replace
NO
NO
Open circuit between
No.SBF-8 (30A) slow blow
fuse and No.C105-1.

HEATER AND AIR CONDITIONING 1-81

BLOWER MOTOR DOES NOT RUN IN CERTAIN POSITION

A 1: (Low)
Blower motor does no
tB 2: (Medium Low) Position
run at
C 3: (Medium Hi)

D 4: (High)
* Checkin
g is performed only when in the malfunction
mode.


Is resist or OK?
YES


Is fan control knob (Fan switch) OK?
YES
Condition:


O
pen circuit between chassis side connector
terminal No. C104-2 and No. B13-3
B Condition :


O
pen circuit between chassis side connector
terminal No. C104-4 and No. B13-6
C Condition:


O
pen circuit between chassis side connector
terminal No. C104-1 and No. B13-5
D Condition:


O
pen circuit between chassis side connector
terminal No. C105-2 a nd No. B13-4
Replace
NO
NO
Replace control leverassembly A

1-82 HEATER AND AIR CONDITIONING

BLOWER MOTOR DOES NOT STOP AT “OFF” POSITION


Is fan control knob (Fan switch) OK?
YES
Short circuit between chassis side connector terminal

No.
C105-2 and No. C104-3
(or)


No. C105-2 and No. B13-4
(or)


No. C104-1 and No. B13-5
(or)


No. C104-4 and No. B13-6

(or)

No. C104-2 and No. B13-3
NO
Replace control lever assembly

HEATER AND AIR CONDITIONING 1-83

AIR CONDITIONING CYCLE TROUBLESHOOTING

TROUBLE POSSIBLE CAUSE CORRECTION
No cooling or
insufficient
cooling
1. Magnetic clutch does not run


Refer to “MAGNETIC CLUTCH”
troubleshooting in this section
2. Compressor is not rotating properly

Drive belt loosened or broken

Adjust the drive belt to the specified
tension or replace the drive belt


Magnetic clutch face is not clean and
slips
Clean the magnetic clutch face or replace




Incorrect clearance between magnetic
drive plate and pulley

Adjust the clearance (Refer to
“COMPRESSOR OVERHAUL”



Compressor oil leaks from shaft seal or
shell

Replace the compressor




Compressor seized

Replace the compressor

3. Insufficient or excessive charge of
refrigerant

Discharge and recover refrigerant.
Recharge to specified amount.
4. Leaks in the refrigerant system




Check refrigerant system for leaks and
repair as necessary
Discharge and recover refrigerant.
Recharge to specified amount.
5. Condenser clogged or insufficient radiation


Clean the condenser or replace as
necessary


Check radiator or condenser fan function

6. Temperature control link unit of the heater
unit defective

Repair the link unit

7. Unsteady operation due to foreign
substance in expansion valve

Replace the expansion valve

8. Poor operation of electronic thermostat


Check electronic thermostat and replace
as necessary
Insufficient
velocity
of cooling air

1. Evaporator clogged or frosted


Check evaporator core and replace or
clean the core
2. Air leaking from cooling unit or air duct

Check evaporator and duct connection,
then repair as necessary

3. Blower motor does not rotate prop-erly


Refer to “FAN CONTROL KNOB (FAN
SWITCH)” troubleshooting in this section

* For the execution of the charging and discharging operation in the table above, refer to the “RECOVERY,
RECYCLING, EVACUATING AND CHARGING” in this section.

1-84 HEATER AND AIR CONDITIONING

f06r300014
CHECKING REFRIGERANT SYSTEM
WITH MANIFOLD GAUGE
Conditions;


Ambient temperature at approx. 30
35
C (86
95
F)


Run the engine at Idling

A/C switch is “ON”


Run the blower motor at “4” (high) position


Temperature control knob sets at “MAX COLD”


Air source selector lever at “CIRC”


Close the all doors
Normal pressures kPa (kg/cm
2 / PSI);
Low-pressure side:
Approx. 127 – 245 (1.3 – 2.5 / 18 – 36)
High-pressure side:
Approx. 1373 – 1670 (14 – 17 / 199 – 242)
Connect the manifold gauge
Low-pressure hose (LOW)  Suction side
High-pressure hose (HI)  Discharge side

HEATER AND AIR CONDITIONING 1-87

MAGNETIC CLUTCH
When the A/C switch and the fan control knob (fan switch) are turned on with the engine running, current flows
through the thermostat and the compressor relay to activate the magnetic clutch.
The air conditioning can be stopped by turning off the A/C switch or the fan control knob (fan switch).
However, even when the air conditioning is in operation, the electronic thermostat, the pressure switch or the ECM
is used to stop the air conditioning temporarily by turning off the magnetic clutch in the prearranged conditions to
reduce the engine load which is being caused by the rise in the engine coolant temperature, and the acceleration of
the vehicle, etc.

1-90 HEATER AND AIR CONDITIONING

MAGNETIC CLUTCH DOES NOT RUN (4JA1L/4JH1-TC)



Replace
YES


Are the A/C thermo (X-15) and heater & A/C (X-11)
and A/C compressor (X-14) relay OK?

Are the No. SBF-8 fuse (30A) and the No. EB-13
(10A) fuses OK
YES


Is the pressure switch (C-24) OK?
YES


Are the A/C switch (B-57) and the fan switch (B-13)
OK?
NO
YES


Is there continuity between the engine harness
connector terminal No.1 (E-3) and engine room harness
connector terminal No.2 (X-14)?

Disconnect the A/C compressor relay.

Turn the ignition switch "ON" (Engine is running)


A/C switch and fan control knob (fan switch "ON")
NO
Replace
NO
Defective switch or insufficient
refrigerant
NO
NO
Does the magnetic clutch
operate?
YES
Replace


Disconnect the magnetic clutch connector.

Is there battery voltage between the engine room harness
connector terminal No.1 (E-3) and ground?
Defective compressor
YESNO
Defective magnetic clutch

HEATER AND AIR CONDITIONING 1-91





Open circuit between the engine
harness connector terminal No.1 (E-3)
and engine room harness connector
terminal No.2 (X-14).
YES


Is there battery voltage between the engine room
harness connector terminal No.1 (X-14) and
ground?
YES


Disconnect the A/C thermo relay.
YES


Is there continuity between the ECM harness
connector terminal No.38 (C-56) and engine
room harness connector terminal No.4 (X-14)?
NO
Open circuit between the No. EB-13
fuse and engine room harness
connector terminal No.1 (X-14).
NO
Open circuit between the engine room
harness connector terminal No.1 (X-
15) and engine room harness
connector terminal No. 3 (X-14).
NO

Is there continuity between the engine room
harness connector terminal No.3 (X-14) and No.1
(X-15)?
YES


Is there continuity between the ECM harness
connector terminal No.30 (C-56) and engine
room harness connector terminal No.2 (X-15)? Open circuit between the engine room
harness connector terminal No.1 (X-
15) and engine room harness
connector terminal No. 3 (X-14).
NO
YES


Is there battery voltage between the engine room
harness connector terminal No.4 (X-15) and
ground?
Open circuit between the ECM
harness connector No. 38 (C-56) and
engine room harness connector
terminal No. 4 (X-14).
NO
YES


Is there continuity between the engine room
harness connector terminal No. 3 (X-15) and the
engine room harness connector terminal No. 1 (C-
24).
Open circuit between the No. EB-13
fuse and engine room harness
connector terminal No. 4 (X-15).
NO


Disconnect the ECM harness connector.


Disconnect the pressure switch?