2007 ISUZU KB P190 relay

1-84 HEATER AND AIR CONDITIONING



RTW 4A0SH000201

Triple 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
(W hen battery voltage is applied between 2 - 4 )
1 - 5 ⋅⋅⋅⋅⋅ Continuity
825r300023

Check for continuity between the relay terminals.
1 - 2 ⋅⋅⋅⋅⋅ No continuity
(W hen battery voltage is applied between 3 - 4 )
1 - 2 ⋅⋅⋅⋅⋅ Continuity




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ISUZU KB P190 2007

HEATER AND AIR CONDITIONING 1-85
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.”



RTW 710LF004201

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ISUZU KB P190 2007

1-86 HEATER AND AIR CONDITIONING
BLOWER MOTOR DOES NOT RUN


Replace
YES
• Is No.SBF-6 (30A) (except C24SE) or No.SBF-8
(30A) (C24SE) 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
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-6 (30A) (except
C24SE) or No.SBF-8 (30A)
(C24SE) slow blow fuse and
No.C105-1.


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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

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

1-100 HEATER AND AIR CONDITIONING
MAGNETIC CLUTCH DOES NOT RUN (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-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
• Is there continuity between the engine harness
connector terminal No.1 (E-3) and the 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
• Is the electronic thermostat (C-55) OK?
YES
Replace
NO


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ISUZU KB P190 2007