2007 ISUZU KB P190 air condition

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

HEATER AND AIR CONDITIONING 1-93
MAGNETIC CLUTCH
W hen 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.


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ISUZU KB P190 2007

1-94 HEATER AND AIR CONDITIONING
4JA1 – T



RTW 710XF000201


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ISUZU KB P190 2007

HEATER AND AIR CONDITIONING 1-95
MAGNETIC CLUTCH DOES NOT RUN (4JA1-T)



Replace
YES
• Are the A/C thermo (X-15) and heater & A/C (X-11)
relay OK?
• Are the No. SBF-6 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
• 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
• Is the electronic thermostat (C-55) OK?
YES
Replace
NO
• Disconnect the A/C thermo relay.
• Is there continuity between the engine room harness
connector terminal No.1 (E-3) and engine room harness
connector terminal No.1 (X-15)?


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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

HEATER AND AIR CONDITIONING 1-97



YES
Open circuit between the No. EB-13
fuse and engine room harness
connector terminal No. 4 (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. 1 (C-24).
NO
YES
• Is there continuity between the engine room
harness connector terminal No.1 (C-55) and the
chassis side harness connector terminal No.5
(B-57) ? or (cooler only) the short connector
terminal No.3 (B-79) and the chassis side
harness connector terminal No.5 (B-57)? 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. 1
(C-24)?
Open circuit between the engine room
harness connector terminal No. 1 (C-
55) or (cooler only) the short
connector No. 3 (B-79) and the
chassis side harness connector
terminal No.5 (B-57). • Is there continuity between the engine room
harness connector (cooler only) terminal No. 4
(C-55) and the chassis side harness connector
terminal No. 11 (B-57)?
YES NO


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ISUZU KB P190 2007

1-98 HEATER AND AIR CONDITIONING


YES
• Disconnect the A/C switch.
• Is there battery voltage between the chassis side
harness connector terminal No. 6 (B-57) and ground (C-
109)?
Open circuit between the engine room
harness connector (cooler only) terminal
No. 4 (C-55) and the chassis side harness
connector terminal No. 11 (B-57).
NO YES
• Is there battery voltage between the chassis side
harness connector terminal No. 10 (B-57) and ground?
Open circuit between the chassis side
harness connector No. 1 (B-79) and the
chassis side harness connector terminal
No. 10 (B-57).
NO
YES
• Defective ECM Open circuit between the No. EB-13 fuse
and the chassis side harness connector
No. 6 (B-57).
NO




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ISUZU KB P190 2007

HEATER AND AIR CONDITIONING 1-99
4JH1 – TC



RTW 710XF000301


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ISUZU KB P190 2007