2007 ISUZU KB P190 CONDENSER

HEATER AND AIR CONDITIONING 1-89
AIR CONDITIONING CYCLE TROUBLESHOOTING

TROUBLE POSSIBLE CAUSE CORRECTION
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

No cooling or
insufficient
cooling
8. Poor operation of electronic thermostat
•
Check electronic thermostat and replace
as necessary
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
Insufficient
velocity
of cooling air
3. Blower motor does not rotate properly
• Refer to “FAN CONTROL KNOB (FAN
SW ITCH)” 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.



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ISUZU KB P190 2007

HEATER AND AIR CONDITIONING 1-91
RESULT SYMPTOM TROUBLE CAUSE CORRECTION
Reduced or no air flow through
the condenser
•
Condenser clogged or dirty
• Radiator (condenser) fan
does not operate properly •
Clean
• Check cooling fan
operation
No bubbles in sight glass when
condenser is cooled by water
(Insufficient cooling)



•
Excessive refrigerant in
system




•
Check sight glass.
(See “Reading Sight
Glass”)
• Discharge and
recover refrigerant.
Recharge to specified
amount
Discharge
(High)
pressure
gauge
abnormally
high
After stopping air conditioning,
pressure drops approx. 196 kPa
(2.0kg/cm
2 / 28psi) quickly •
Air in system
•
Evacuate and charge
refrigerant system
Insufficient cooling and excessive
bubbles in the sight glass





•
Insufficient refrigerant in
system





•
Check sight glass.
(See “Reading Sight
Glass”)
• Check for leaks
• Discharge and
recover refrigerant.
Recharge to specified
amount
Low pressure gauge indicates
vacuum •
Clogged or defective
expansion valve •
Replace the
expansion valve
Frost or dew on refrigerant line
before and after receiver/ drier or
expansion valve, and low pres-
sure gauge indicates vacuum •
Restriction caused by debris
or moisture in receiver/drier

•
Check system for
restriction and
replace receiver/drier

Discharge
(High)
pressure
gauge
abnormally
low
After turning off air conditioning,
high and low pressure gauge
balanced quickly
•
Compressor seal defective
• Poor compression due to
defective compressor
gasket •
Replace or repair
compressor
Low pressure gauge is lowered
after condenser is cooled by
water
•
Excessive refrigerant in
system

•
Discharge and
recover refrigerant
Recharge to specified
amount
Low pressure hose temperature
around the compressor refrigerant
line connector is lower than
around evaporator

•
Unsatisfactory valve
operation due to defective
temperature sensor of
expansion valve
• Expansion valve opens too
long •
Replace the
expansion valve




After turning off air conditioning,
high and low pressure gauge is
balanced quickly •
Compressor gasket is
defective
•
Replace


Suction
(Low)
pressure
gauge
abnormally
high
Air conditioning turns off before
passenger compartment is
sufficiently
cool •
Electronic thermostat
defective
•
Check the electronic
thermostat and
replace as necessary


* For the charging and discharging operations in the table above, refer to “RECOVERY, RECYCLING,
EVACUATION AND CHARGING” in this section.

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ISUZU KB P190 2007

1-92 HEATER AND AIR CONDITIONING
RESULT SYMPTOM TROUBLE CAUSE CORRECTION
Condenser is not hot and
excessive bubble in sight glass





•
Insufficient refrigerant






•
Check sight
glass.(See “Reading
Sight Glass”)
• Check for leaks
• Discharge and
recover refrigerant.
Recharge to specified
amount
Frost on the expansion valve inlet
line •
Expansion valve clogged
•
Replace the
expansion valve
A distinct difference in
temperature between the inlet and
outlet refrigerant lines of the
receiver/drier •
Receiver/drier clogged


•
Replace the receiver/
drier


Expansion valve outlet refrigerant
line is not cold and low-pressure
gauge indicates vacuum

•
The temperature sensor of
the expansion valve is
defective, and the valve
cannot regulate the correct
flow of the refrigerant •
Replace the
expansion valve



Discharge temperature is low and
air flow from vents is restricted
•
Frozen evaporator core fins

•
Check electronic
thermostat and
replace as necessary
Suction
(Low)
pressure
abnormally
low

Low-pressure gauge reading is
low, or a vacuum reading may be
shown •
Clogged or blocked
refrigerant line
•
Replace refrigerant
line
No bubbles in sight glass after
condenser is cooled by water
(Insufficient cooling)



•
Excessive refrigerant in
system




•
Check sight
glass.(See “Reading
Sight Glass”)
• Discharge and
recover refrigerant.
Recharge to specified
amount
Reduce air flow through con-
denser
•
Condenser clogged
• Radiator (condenser) fan
does not rotate properly •
Clean
• Check cooling fan
operation
Suction
(Low) and
Discharge
(High)
pressure
abnor-
mally
high

Suction (Low) pressure hose is
not cold •
Air in system • Evacuate and charge
refrigerant
Suction
(Low) and
Discharge
(High)
pres-sure
abnor-
mally
low Insufficient cooling and excessive
bubbles in the sight glass •
Insufficient refrigerant in
system
•
Check sight glass.
(See “Reading Sight
Glass”)
• Check for leaks
• Discharge and
recover refrigerant.
Recharge to specified
amount

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ISUZU KB P190 2007

1-96 HEATER AND AIR CONDITIONING




Open circuit between the engine room
harness connector terminal No.1 (X-
15).
NOYES
• Is there continuity between the engine room
harness connector terminal No.2 (X-15) and
ground?
YES
• Is there battery voltage between the engine room
harness connector terminal No.3 (X-15) and
ground? Open circuit between the engine room
harness connector terminal No. 2 (X-
15).
NO
YES
• Is there continuity between the engine room
harness connector terminal No. 5 (X-15) and the
engine room harness connector terminal No. 2 (C-
24)?
Open circuit between the No. EB-13
fuse and the engine room harness
connector terminal No. 3 (X-15).
NO
• Disconnect the pressure switch.
• Disconnect the condenser fan relay connector
condenser fan.
• Is there battery voltage between the engine room
harness connector terminal No.4 (C-24) and
ground? Open circuit between the condenser
fan relay No. 3 (X-13) and engine
room harness connector terminal No.3
(C-24).
• Is there continuity between the relay terminal
No.3 (X-13)and engine room harness connector
terminal No.3 (C-24)?
Open circuit between the engine room
harness connector terminal No. 5 (X-
15) and the engine room harness
connector terminal No. 2 (C-24).
YES NO
YES NO



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ISUZU KB P190 2007

1-102 HEATER AND AIR CONDITIONING



YES
• Disconnect the condenser fan relay connector
condenser fan.
YES
• Is there battery voltage between the engine
room harness connector terminal No.3 (C-
24) and ground? Open circuit between the condenser
fan relay No.3 (X-9) and the engine
room harness connector terminal No.
4 (C-24).
NO
• Is there continuity between the relay terminal
No. 3 (X-9) and engine room harness connector
terminal No.4 (C-24)?
YES
Open circuit between the No. EB-13
fuse and engine room harness
connector terminal No. 3 (C-24).
NO
YES
• Is there battery voltage between the engine
room harness connector terminal No.3 (C-55)
and ground? Open circuit between the engine room
harness connector terminal No. 2 (C-
55) and the engine room harness
connector terminal No. 2 (C-24).
NO
YES
• Is there continuity between the engine room
harness connector terminal No.1 (C-55) and
ground (C-109) ? Open circuit between the No. EB-13
fuse and the engine room harness
connector terminal No. 3 (C-55).
NO
• connect the A/C thermo relay connector.
• Disconnect the electronic thermostat.
• Is there continuity between the engine room
harness connector terminal No. 2 (C-55) and the
engine room harness connector terminal No. 2
(C-24)?
Open circuit between the engine room
harness connector terminal No. 5 (X-
15) and the engine room harness
connector terminal No. 1 (C-24).
NO


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ISUZU KB P190 2007

HEATER AND AIR CONDITIONING 1-107



YES
• Disconnect the condenser fan relay.
YES
• Is there battery voltage between the engine
room harness connector terminal No.3 (C-
24) and ground? Open circuit between the condenser
fan relay No.3 (X-9) and the engine
room harness connector terminal No.
4 (C-24).
NO
• Is there continuity between the relay terminal
No. 3 (X-9) and engine room harness connector
terminal No.4 (C-24)?
YES
Open circuit between the No. EB-13
fuse and engine room harness
connector terminal No. 3 (C-24).
NO
YES
• Is there battery voltage between the engine
room harness connector terminal No.3 (C-55)
and ground? Open circuit between the engine room
harness connector terminal No. 2 (C-
24) and the engine room harness
connector terminal No. 2 (C-55).
NO
YES
• Is there continuity between the engine room
harness connector terminal No.1 (C-55) and
ground (C-109) ? or (cooler only) the short
connector terminal No.3 (B-79) and ground (C-
109
)?
Open circuit between the No. EB-13
fuse and the engine room harness
connector terminal No. 3 (C-55).
NO
• connect the A/C thermo relay connector.
• Disconnect the electronic thermostat.
• Is there continuity between the engine room
harness connector terminal No. 2 (C-55) and the
engine room harness connector terminal No. 2
(C-24)?
Open circuit between the engine room
harness connector terminal No. 5 (X-
15) and the engine room harness
connector terminal No. 1 (C-24).
NO


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ISUZU KB P190 2007

1-112 HEATER AND AIR CONDITIONING



YES
• Disconnect the condenser fan relay.
YES
• Is there battery voltage between the engine
room harness connector terminal NO.3 (C-
24) and ground? Open circuit between the condenser
fan relay No.3 (X-9) and the engine
room harness connector terminal No.
4 (C-24).
NO
• Is there continuity between the relay terminal
No. 3 (X-9) and engine room harness connector
terminal No.4 (C-24)?
YES
Open circuit between the No. EB-13
fuse and engine room harness
connector terminal No. 3 (C-24).
NO
YES
• Is there battery voltage between the engine
room harness connector terminal No.3 (C-55)
and ground? Open circuit between the engine room
harness connector terminal No. 2 (C-
24) and the engine room harness
connector terminal No. 2 (C-55).
NO
YES
• Is there continuity between the engine room
harness connector terminal No.1 (C-55) and
ground (C-109)? Open circuit between the No. EB-13
fuse and the engine room harness
connector terminal No. 3 (C-55).
NO
• connect the A/C thermo relay connector.
• Disconnect the electronic thermostat.
• Is there continuity between the engine room
harness connector terminal No. 2 (C-55) and the
engine room harness connector terminal No. 2
(C-24)?
Open circuit between the engine room
harness connector terminal No. 5 (X-
15) and the engine room harness
connector terminal No. 1 (C-24).
NO


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ISUZU KB P190 2007

HEATER AND AIR CONDITIONING 1-117


YES
• Disconnect the condenser fan relay connector condenser
fan.
YES
• Is there battery voltage between the engine room
harness connector terminal NO. 3 (C-24) and ground?Open circuit between the condenser fan
relay No.3 (X-10) and engine room harness
connector terminal No. 4 (C-24).
NO
• Is there continuity between the relay terminal No. 3 (X-
10) and engine room harness connector terminal No.4
(C-24)?
YES
Open circuit between the No. EB-13 fuse
and engine room harness connector
terminal No. 3 (C-24).
NO
YES
• Is there continuity between the engine room harness
connector terminal No. 2 (C-55) and the engine room
harness connector terminal No. 2 (C-24)?
Open circuit between the engine room
harness connector terminal No. 4 (X-15)
and the engine room harness connector
terminal No. 1 (C-24).
NO
• Disconnect the pressure switch.
• Is there continuity between the engine room harness
connector terminal No. 4 (X-15) and the engine room
harness connector terminal No. 1 (C-24).
Open circuit between the No. EB-13 fuse
and the engine room harness connector
terminal No. 2 (X-15).
NO
• Connect the A/C thermo relay connector.
• Disconnect the electronic thermostat.
Open circuit between the engine room
harness connector terminal No.3 (X-15)
and the engine room harness connector
terminal No. 1 (C-24).
NO





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ISUZU KB P190 2007