heater ISUZU TF SERIES 2004 Workshop Manual
Page 3097 of 4264
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.
Page 3098 of 4264
1-88 HEATER AND AIR CONDITIONING
4JA1 – L
RTW410LF000401
Page 3099 of 4264
HEATER AND AIR CONDITIONING 1-89
4JH1 – TC
RTW410LF000101
Page 3100 of 4264
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
Page 3101 of 4264
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?
Page 3102 of 4264
1-92 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 4JH1TC No.4 (X-6) 4JA1L
No. 3 (X-13) and engine room harness
connector terminal No. 4 (X-14).
NO
Is there continuity between the relay terminal
4JH1TC No. 4 (X-6) 4JA1L No.3 (X-13)and
engine room harness connector terminal No.4
(C-24)?
YES
connect the A/C thermo relay connector.
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)
dd?
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) ? or (cooler only) the short
connector terminal No.3 (B-79) and ground (C-
109
)?
Open circuit between the No. EB-13
fuse and engine room harness
connector terminal No. 3 (C-55).
NO
Disconnect the electronic themostat.
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 and engine room
harness connector terminal No. 3 (X-
15) and the engine room harness
connector terminal No. 1(C-24).
NO
Page 3103 of 4264
HEATER AND AIR CONDITIONING 1-93
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 terminal No. 1 (C-55) or
(cooler only) the short connector No. 3 (B-
79) and ground (C-109).
NO YES
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).
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
chassis side harness connector terminal
No. 10 (B-57).
NO
YES
Is the electronic themostat OK? Open circuit between the No. EB-13 fuse
and the chassis side harness connector
No. 6 (B-57).
NO
YES
Defective ECM Replace electronic thermostat
NO
Page 3104 of 4264
1-94 HEATER AND AIR CONDITIONING
6VE1
RTW410XF000201
Page 3105 of 4264
HEATER AND AIR CONDITIONING 1-95
MAGNETIC CLUTCH DOES NOT RUN
Replace
YES
Are the A/C thermo (X-15), 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-2) 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-2) and ground?
Defective compressor
YESNO
Defective magnetic clutch
Page 3106 of 4264
1-96 HEATER AND AIR CONDITIONING
Open circuit between the engine
harness connector terminal No.1 (E-
13) 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. 11 (E-61) 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 No.EB-13
fuse and engine room harness
connector terminal No. 3 (X-14).
NO
Is there battery voltage the engine room harness
connector terminal No.3 (X-14) and ground?
YES
Is there continuity between the ECM harness
connector terminal No.31 (E-61) and engine
room harness connector terminal No.1 (X-15)? Open circuit between the ECM
harness connector No. 11 (E-61) and
engine room harness connector
terminal No. 4 (X-14).
NO
YES
Is there battery voltage between the engine room
harness connector terminal No.3 (X-15) and
ground?
Open circuit between the No. EB-13
fuse and engine room harness
connector terminal No. 2 (X-15).
NO
YES
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 engine room harness
connector terminal No. 3 (X-15).
NO
Disconnect the ECM harness connector.
Disconnect the pressure switch.