ISUZU TROOPER 1998 Service Manual PDF

00 Ð 22 SERVICE INFORMATION
CERAMIC HEATER DOES NOT STOP
WHEN THE IGNITION SW. ÒOFFÓ, DOES CERAMIC HEATER
STOP?
YESNO
CERAMIC HEATER RELAY DEFECTIVE·SHORT CIRCUIT BETWEEN CHASSIS SIDE RELAY TERMINAL
NO. X12-3 AND CHASSIS SIDE CONNECTOR TERMINALNO. B49-1

SERVICE INFORMATION 00 Ð 23
AIR CONDITIONING CYCLE TROUBLESHOOTING
No cooling or insuffi-
cient cooling
Insufficient velocity
of cooling air1. Magnetic clutch does not run
2. Compressor is not rotating properly
·Drive belt loosened or broken
·Magnetic clutch face is not
clean and slips
·Incorrect clearance between
magnetic drive plate and pulley
·Compressor oil leaks from shaft
seal or shell
·Compressor seized
3. Insufficient or excessive charge of
refrigerant
4. Leaks in the refrigerant system
5. Condenser clogged or insufficient
radiation
6. Temperature control link unit of the
heater unit defective
7. Unsteady operation due to foreign
substance in expansion valve
8. Poor operation of electronic thermo-
stat
1. Evaporator clogged or frosted
2. Air leaking from cooling unit or air
duct
3. Blower motor does not rotate prop-
erly·Refer to ÒMAGNETIC CLUTCHÓ
troubleshooting
·Adjust the drive belt to the specified
tension or replace the drive belt
·Clean the magnetic clutch face or
replace
·Adjust the clearance (Refer to
Section 1D ÒCOMPRESSOR OVER-
HAULÓ
·Replace the compressor
·Replace the compressor
·Discharge and recover refrigerant.
Recharge to specified amount.
·Check refrigerant system for leaks
and repair as necessary
Discharge and recover refrigerant.
Recharge to specified amount.
·Clean the condenser or replace as
necessary
·Check radiator or condenser fan
function
·Repair the link unit
·Replace the expansion valve
·Check electronic thermostat and
replace as necessary
·Check evaporator core and replace
or clean the core
·Check evaporator and duct connec-
tion, then repair as necessary
·Refer to Section 00 for ÒFAN
CONTROL KNOB (FAN SWITCH)Ó
troubleshooting
* For the execution of the charging and discharging operation in the table above, refer to the ÒRECOVERY,
RECYCLING, EVACUATING AND CHARGINGÓ in section 1B.
TROUBLEPOSSIBLE CAUSECORRECTION

00 Ð 24 SERVICE INFORMATION
CHECKING REFRIGERANT SYSTEM
WITH MANIFOLD GAUGE
Conditions;
·Ambient temperature at approx. 25 ~30°C (77
~86°F)
·Run the engine at Idling
·A/C switch is ÒONÓ
·Run the blower motor at Ò4Ó (high) position
·Temperature control knob sets at ÒMAX COLDÓ
·Air source selector lever at ÒCIRCÓ
·Close the all doors
Normal pressures kpa (kgácm
2/ PSI);
Low-pressure side:
Approx. 147 Ð 294 (1.5 Ð 3.0 / 21 Ð 43)
High-pressure side:
Approx. 1373 Ð 1863 (14 Ð 19 / 199 Ð 270 )
Connect the manifold gauge
Low-pressure hose (LOW)~Suction side
High-pressure hose (HI)~Discharge side (Low side) (High side)

RESULT SYMPTOM TROUBLE CAUSE CORRECTION
SERVICE INFORMATION 00 Ð 25
Reduced or no air flow through
the condenser
No bubbles in sight glass when
condenser is cooled by water
(Insufficient cooling)
After stopping air conditioning,
pressure drops approx. 196 kPa
(28 PSI) quickly
Insufficient cooling and excessive
bubbles in the sight glass
Low pressure gauge indicates
vacuum
Frost or dew on refrigerant line
before and after receiver/ drier or
expansion valve, and low pres-
sure gauge indicates vacuum
After turning off air conditioning,
high and low pressure gauge
balanced quickly
Low pressure gauge is lowered
after condenser is cooled by
water
Low pressure hose temperature
around the compressor refriger-
ant line connector is lower than
around evaporator
After turning off air conditioning,
high and low pressure gauge is
balanced quickly
Air conditioning turns off before
passenger compartment is suffi-
ciently cool·Condenser clogged or dirty
·Radiator (condenser) fan
does not operate properly
·Excessive refrigerant in
system
·Air in system
·Insufficient refrigerant in
system
·Clogged or defective expan-
sion valve
·Restriction caused by debris
or moisture in receiver/drier
·Compressor seal defective
·Poor compression due to
defective compressor gasket
·Excessive refrigerant in
system
·Unsatisfactory valve opera-
tion due to defective temper-
ature sensor of expansion
valve
·Expansion valve opens too
long
·Compressor gasket is defec-
tive
·Electronic thermostat defec-
tive·Clean
·Check cooling fan
operation
·Check sight glass.
(See ÒReading Sight
GlassÓ)
·Discharge and
recover refrigerant.
Recharge to speci-
fied amount
·Evacuate and
charge refrigerant
system
·Check sight glass.
(See ÒReading Sight
GlassÓ)
·Check for leaks
·Discharge and
recover refrigerant.
Recharge to speci-
fied amount
·Replace the expan-
sion valve
·Check system for
restriction and
replace
receiver/drier
·Replace or repair
compressor
·Discharge and
recover refrigerant
Recharge to speci-
fied amount
·Replace the expan-
sion valve
·Replace
·Check the electronic
thermostat and
replace as neces-
saryDischarge
(High) pres-
sure gauge
abnormally
high
Discharge
(High) pres-
sure gauge
abnormally
low
Suction
(Low) pres-
sure gauge
abnormally
high
* For the charging and discharging operations in the table above, refer to ÒRECOVERY, RECYCLING,
EVACUATION AND CHARGINGÓ in this section.

RESULT SYMPTOM TROUBLE CAUSE CORRECTION
Suction
(Low) pres-
sure abnor-
mally low
Suction
(Low) and
Discharge
(High) pres-
sure abnor-
mally high
Suction
(Low) and
Discharge
(High) pres-
sure abnor-
mally low
00 Ð 26 SERVICE INFORMATION
·Check sight
glass.(See ÒReading
Sight GlassÓ)
·Check for leaks
·Discharge and
recover refrigerant.
Recharge to speci-
fied amount
·Replace the expan-
sion valve
·Replace the receiv-
er/drier
·Replace the expan-
sion valve
·Check electronic
thermostat and
replace as necessary
·Replace refrigerant
line
·Check sight
glass.(See ÒReading
Sight GlassÓ)
·Discharge and
recover refrigerant.
Recharge to speci-
fied amount
·Clean
·Check cooling fan
operation
·Evacuate and charge
refrigerant
·Check sight glass.
(See ÒReading Sight
GlassÓ)
·Check for leaks
·Discharge and
recover refrigerant.
Recharge to speci-
fied amount·Insufficient refrigerant
·Expansion valve clogged
·Receiver/drier clogged
·The temperature sensor of
the expansion valve is defec-
tive, and the valve cannot
regulate the correct flow of
the refrigerant
·Frozen evaporator core fins
·Clogged or blocked refriger-
ant line
·Excessive refrigerant in
system
·Condenser clogged
·Radiator (condenser) fan
does not rotate properly
·Air in system
·Insufficient refrigerant in
systemCondenser is not hot and exces-
sive bubble in sight glass
Frost on the expansion valve inlet
line
A distinct difference in tempera-
ture between the inlet and outlet
refrigerant lines of the
receiver/drier
Expansion valve outlet refrigerant
line is not cold and low-pressure
gauge indicates vacuum
Discharge temperature is low and
air flow from vents is restricted
Low-pressure gauge reading is
low, or a vacuum reading may be
shown
No bubbles in sight glass after
condenser is cooled by water
(Insufficient cooling)
Reduce air flow through con-
denser
Suction (Low) pressure hose is
not cold
Insufficient cooling and excessive
bubbles in the sight glass

SERVICE INFORMATION 00 Ð 27
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 com-
pressor 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 oper-ation, the electronic thermostat, the pressure switch
or the PCM (6VD1/6VE1 Engine) is used to stop the
air conditioning temporarily by turning off the mag-
netic clutch in the prearranged conditions to reduce
the engine load which is being caused by the rise in
the engine coolant temperature, and the accelera-
tion of the vehicle, etc.
123
45 6
RELAY; A/C
B-36C-20
10A
A/C FL-1
80A
MAIN
1
2
B-2
C-25
2
4
X-5
1
3 (3)
(1)
4
13
24
1
A/C SW.
FAN SW.
I-23
PRESSURE
SW.
RELAY;
THERMOSTAT
B-2
X-7 C-25
C-1C-3E-3I-23
BATTERY
X-7
RELAY: A/C
COMPRESSOR
1
E-3
MAGNETIC
CLUTCHMg
OFF
I-18
2
6
1
321123
12
3412
11
213
5 46
I-18
X-5
B-1(LHD) (RHD)
B-1
1
2 34
W/ CONDENSER
FAN
2
4
1
3
C-3PCM (E15)
C-1PCM (B14)
3
1
2
ELECTRONIC
THERMOSTAT
I-42
I-42B-36
Pin number with ( ); RHD
A1 A2 A3 A4 A5 A6 A7 A8 A9A10 A11 A12 A13 A14 A15 A16B1 B2 B3 B4 B5 B6 B7 B8 B9B10 B11 B12 B13 B14 B15 B16E1 E2 E3 E4 E5 E6 E7 E8 E9E10 E11 E12 E13 E14 E15 E16F1 F2 F3 F4 F5 F6 F7 F8 F9F10 F11 F12 F13 F14 F15 F16
6VD1/6VE1 ENGINE
D08RY00295

00 Ð 28 SERVICE INFORMATION
MAGNETIC CLUTCH DOES NOT RUN
·TURN THE STARTER SWITCH ON AND START THE
ENGINE.
·TURN THE FAN SWITCH ON.
·DOES THE BLOWER MOTOR RUN?
YESNO
REFER TO THE DIAGNOSIS PROCEDURE FOR
ÒBLOWER MOTOR DOES NOT RUNÓ.·IS THE FUSE C-20 (10A) NORMAL?
YESNO
REPLACE THE FUSE.·DISCONNECT THE A/C SWITCH CONNECTOR AND
REMOVE THE A/C SWITCH.
·IS THE A/C SWITCH NORMAL?
YESNO
YESNO
REPAIR AN OPEN CIRCUIT BETWEEN THE
FUSE C-20 AND I23-2.·REINSTALL THE A/C SWITCH AND DISCONNECT THE DUAL
PRESSURE SWITCH (OR TRIPLE PRESSURE SWITCH) CON-
NECTOR C25.
·TURN THE A/C SWITCH ON.
·IS THE BATTERY VOLTAGE APPLIED AT HARNESS SIDE
CONNECTOR C25-1?
YESNO
REPLACE THE SWITCH.·RECONNECT THE CONNECTOR C25 AND DISCONNECT THE
A/C THERMO RELAY CONNECTOR X5.
·IS THERE CONTINUITY BETWEEN HARNESS SIDE CONNEC-
TOR C25-2 AND X5-1?
YESNO
REPAIR AN OPEN CIRCUIT BETWEEN I23-6
AND C25-1.·IS THE DUAL PRESSURE SWITCH (OR TRIPLE PRESSURE
SWITCH) NORMAL?
YESNO
REPAIR OR REPLACE THE SWITCH.·IS THE BATTERY VOLTAGE APPLIED AT HARNESS SIDE
CONNECTOR I23-2?

SERVICE INFORMATION 00 Ð 29
·IS THE BATTERY VOLTAGE APPLIED AT HARNESS SIDE
CONNECTOR X5-2?REPAIR AN OPEN CIRCUIT.
YESNO
·IS THE A/C THERMO RELAY NORMAL?REPAIR AN OPEN CIRCUIT BETWEEN THE
FUSE C-20 AND X5-2.
YESNO
·DISCONNECT THE ELECTRONIC THERMOSTAT CONNEC-
TOR I42.
·IS THE BATTERY VOLTAGE APPLIED AT HARNESS SIDE
CONNECTOR I42-3?
YESNO
·IS THERE CONTINUITY BETWEEN HARNESS SIDE CON-
NECTOR X5-3 AND I42-1?REPAIR AN OPEN CIRCUIT BETWEEN I23-6
AND I42-3.
YESNO
·DISCONNECT THE PCM CONNECTORS.
·IS THERE CONTINUITY BETWEEN HARNESS SIDE CON-
NECTOR X5-4 AND PCM C3-E15?REPAIR AN OPEN CIRCUIT.
YESNO
·IS THERE CONTINUITY BETWEEN HARNESS SIDE CON-
NECTOR I42-2 AND THE GROUND?REPAIR AN OPEN CIRCUIT.
YESNO
·DISCONNECT THE A/C COMPRESSOR RELAY CONNEC-
TOR X7.
·IS THE BATTERY VOLTAGE APPLIED AT HARNESS SIDE
CONNECTOR X7-1 AND X7-2?REPLACE THE ELECTRONIC THERMOSTAT.
YESNO
·RECONNECT X5 AND I42.
·IS THE BATTERY VOLTAGE APPLIED AT HARNESS SIDE
CONNECTOR PCM C3-E15?REPAIR AN OPEN CIRCUIT.
REPLACE THE RELAY.

00 Ð 30 SERVICE INFORMATION
YESNO
REPAIR AN OPEN CIRCUIT BETWEEN THE
FUSE C-20 AND X7-1 (OR X7-2).·DIS CONNECT THE MAGNETIC CLUTCH CONNECTOR E3.
·CONNECT THE BATTERY WITH MAGNETIC CLUTCH SIDE
CONNECTOR E3-1.
·DOES THE MAGNETIC CLUTCH WORK?
YESNO
NO
REPAIR OR REPLACE THE MAGNETIC CLUTCH.·IS THERE CONTINUITY BETWEEN HARNESS SIDE CON-
NECTOR X7-4 AND E3-1?
YES
REPAIR AN OPEN CIRCUIT.
REPAIR AN OPEN CIRCUIT.
REPAIR AN OPEN CIRCUIT.
·IS THERE CONTINUITY BETWEEN HARNESS SIDE CON-
NECTOR X7-3 AND PCM C1-B14?
YESNO
NO
·IS THERE CONTINUITY BETWEEN HARNESS SIDE CON-
NECTOR X5-4 AND PCM C3-E15?
YES
REPLACE THE PCM.

SERVICE INFORMATION 00 Ð 31
4JG2 ENGINE
123
45 6
RELAY; A/C
B-36C-20
(LHD) 10A
A/C FL-1
80A
MAIN
1
2
B-2
C-25
2
4
X-5
1
3
4
13
24
1
A/C SW.
FAN SW.
I-23
PRESSURE
SW.
RELAY;
THERMO
B-2
C-25E-3I-23
BATTERY
3
1
2ELECTRONIC
THERMOSTAT
1
E-3
MAGNETIC
CLUTCHMg
OFF
I-18
2
6
1
321123
12
34
121
213
5 46
I-18
X-5
B-1
(LHD)
(RHD)
B-1
1
2 34
W/ CONDENSER
FAN
I-42
I-42B-36
D08RY00169