Isuzu KB P190. Manual - part 32

1-94  HEATER AND AIR CONDITIONING 

4JA1 – T 

  

 

 

RTW710XF000201 

 

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  

YES

NO 

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)? 

 

1-96  HEATER AND AIR CONDITIONING 

 

 
 
 

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

NO

YES 

• 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

 

 

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