Isuzu KB P190. Service manual — part 36

1-110 HEATER AND AIR CONDITIONING

MAGNETIC CLUTCH DOES NOT RUN (4JJ1-TC Standard Output, 4JJ1-TC

High Output, 4JK1-TC High Output LHD MODEL)

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-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

YES

NO

Defective magnetic clutch

• Is the electronic thermostat (C-55) OK?

YES

Replace

NO

HEATER AND AIR CONDITIONING 1-111

Open circuit between the engine
harness connector terminal No.1 (E-3)
and the 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.55 (C-58) and the engine
room harness connector terminal No.5 (X-14)?

NO

Open circuit between the No. EB-13
fuse and the engine room harness
connector terminal No.1 (X-14).

NO

Open circuit between the engine room
harness connector terminal No.3 (X-
14) and the engine room harness
connector terminal No. 1 (X-15).

NO

• Is there continuity between the engine room
harness connector terminal No.3 (X-14) and the
engine room harness connector terminal No.1 (X-
15)?

YES

• Is there continuity between the ECM harness
connector terminal No.4 (C-58) and the engine
room harness connector terminal No.1 (X-15)?

Open circuit between the ECM
harness connector terminal No.55 (X-
58) and the engine room harness
connector terminal No. 5 (X-14).

NO

YES

• Is there battery voltage between the engine room
harness connector terminal No.2 (X-15) and
ground?

Open circuit between the ECM
harness connector terminal No. 4 (C-
58) and the engine room harness
connector terminal No. 1 (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. 1 (C-
24)?

Open circuit between the No. EB-13
fuse and the engine room harness
connector terminal No. 2 (X-15).

NO

• Disconnect the ECM harness connector.

• Disconnect the pressure switch.

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

HEATER AND AIR CONDITIONING 1-113

YES

• Is the electronic thermostat OK?

Open circuit between the engine room
harness connector terminal No. 1 (C-55)
and ground (C-109).

NO

YES

• Disconnect the A/C switch.

• Is there battery voltage between the chassis side
harness connector terminal No. 6 (B-57) and ground?

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