Isuzu KB P190. Manual - part 33

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 

 

 

 

HEATER AND AIR CONDITIONING  1-99 

4JH1 – TC 

 

 

 

 

 

RTW710XF000301 

 

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  

YES

NO 

Defective magnetic clutch  

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

YES 

Replace 

NO 

 

HEATER AND AIR CONDITIONING  1-101 

 

 
 
 

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.38 (C-56) 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.2 (X-
15) and the 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.2 
(X-15)? 

YES 

• Is there continuity between the ECM harness 
connector terminal No.33 (C-56) and the engine 
room harness connector terminal No.1 (X-15)? 

Open circuit between the ECM 
harness connector terminal No.38 (C-
56) 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.3 (X-15) and 
ground? 

Open circuit between the ECM 
harness connector No. 33 (C-56) 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. 3 (X-15). 

NO

• Disconnect the ECM harness connector. 

• Disconnect the pressure switch?