2007 ISUZU KB P190 air condition

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 1-87
BLOWER MOTOR DOES NOT RUN IN CERTAIN POSITION

A 1: (Low)
Blower motor does not
B 2: (Medium Low) Position
run at
C 3: (Medium Hi)

D 4: (High)
* Checkin
g is performed only when in the malfunction
mode.
•
Is resistor OK?
YES
•
Is fan control knob (Fan switch) OK?
YES
Condition:
•
O
pen circuit between chassis side connector
terminal No. C104-2 and No. B13-3
B Condition :
•
O
pen circuit between chassis side connector
terminal No. C104-4 and No. B13-6
C Condition:
•
O
pen circuit between chassis side connector
terminal No. C104-1 and No. B13-5
D Condition:
•
O
pen circuit between chassis side connector
terminal No. C105-2 and No. B13-4
Replace
NO
NO
Replace control leverassembly A


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ISUZU KB P190 2007

1-88 HEATER AND AIR CONDITIONING
BLOWER MOTOR DOES NOT STOP AT “OFF” POSITION

•
Is fan control knob (Fan switch)OK?

YES


Check the circuit between chassis side connector terminals
for short to GND
•
No.


C105-2 and No. C104-3

(or)

•
No

. C105-2 and No. B13-4
(or)

•
No

. C104-1 and No. B13-5
(or)

•
No

. C104-4 and No. B13-6
(or)

•
No

. C104-2 and No. B13-3
NO
Replace control lever assembly



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ISUZU KB P190 2007

HEATER AND AIR CONDITIONING 1-89
AIR CONDITIONING CYCLE TROUBLESHOOTING

TROUBLE POSSIBLE CAUSE CORRECTION
1. Magnetic clutch does not run
•
Refer to “MAGNETIC CLUTCH”
troubleshooting in this section
2. Compressor is not rotating properly
• Drive belt loosened or broken •
Adjust the drive belt to the specified
tension or replace the drive belt
• Magnetic clutch face is not clean and
slips •
Clean the magnetic clutch face or replace

• Incorrect clearance between magnetic
drive plate and pulley •
Adjust the clearance (Refer to
“COMPRESSOR OVERHAUL”)
• Compressor oil leaks from shaft seal or
shell •
Replace the compressor

• Compressor seized • Replace the compressor
3. Insufficient or excessive charge of
refrigerant •
Discharge and recover refrigerant.
Recharge to specified amount.
4. Leaks in the refrigerant system


•
Check refrigerant system for leaks and
repair as necessary
Discharge and recover refrigerant.
Recharge to specified amount.
5. Condenser clogged or insufficient radiation

•
Clean the condenser or replace as
necessary
• Check radiator or condenser fan function
6. Temperature control link unit of the heater
unit defective •
Repair the link unit
7. Unsteady operation due to foreign
substance in expansion valve •
Replace the expansion valve

No cooling or
insufficient
cooling
8. Poor operation of electronic thermostat
•
Check electronic thermostat and replace
as necessary
1. Evaporator clogged or frosted
•
Check evaporator core and replace or
clean the core
2. Air leaking from cooling unit or air duct
•
Check evaporator and duct connection,
then repair as necessary
Insufficient
velocity
of cooling air
3. Blower motor does not rotate properly
• Refer to “FAN CONTROL KNOB (FAN
SW ITCH)” troubleshooting in this section

* For the execution of the charging and discharging operation in the table above, refer to the “RECOVERY,
RECYCLING, EVACUATING AND CHARGING” in this section.



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ISUZU KB P190 2007

1-90 HEATER AND AIR CONDITIONING
f06r300014
CHECKING REFRIGERANT SYSTEM
WITH MANIFOLD GAUGE
Conditions;
• Ambient temperature at approx. 30 ∼35 °C (86 ∼95 °F)
• Run the engine at Idling
• A/C switch is “ON”
• Run the blower motor at “4” (high) position
• Temperature control knob sets at “MAX COLD”
• Air source selector lever at “CIRC”
• Close the all doors
Normal pressures kPa (kg/cm
2 /psi);
Low-pressure side: Approx. 127 – 245 (1.3 – 2.5 / 18 – 36)
High-pressure side: Approx. 1373 – 1670 (14 – 17 / 199 – 242)
Connect the manifold gauge
Low-pressure hose (LOW ) ∼ Suction side
High-pressure hose (HI) ∼ Discharge side



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ISUZU KB P190 2007

HEATER AND AIR CONDITIONING 1-91
RESULT SYMPTOM TROUBLE CAUSE CORRECTION
Reduced or no air flow through
the condenser
•
Condenser clogged or dirty
• Radiator (condenser) fan
does not operate properly •
Clean
• Check cooling fan
operation
No bubbles in sight glass when
condenser is cooled by water
(Insufficient cooling)



•
Excessive refrigerant in
system




•
Check sight glass.
(See “Reading Sight
Glass”)
• Discharge and
recover refrigerant.
Recharge to specified
amount
Discharge
(High)
pressure
gauge
abnormally
high
After stopping air conditioning,
pressure drops approx. 196 kPa
(2.0kg/cm
2 / 28psi) quickly •
Air in system
•
Evacuate and charge
refrigerant system
Insufficient cooling and excessive
bubbles in the sight glass





•
Insufficient refrigerant in
system





•
Check sight glass.
(See “Reading Sight
Glass”)
• Check for leaks
• Discharge and
recover refrigerant.
Recharge to specified
amount
Low pressure gauge indicates
vacuum •
Clogged or defective
expansion valve •
Replace the
expansion valve
Frost or dew on refrigerant line
before and after receiver/ drier or
expansion valve, and low pres-
sure gauge indicates vacuum •
Restriction caused by debris
or moisture in receiver/drier

•
Check system for
restriction and
replace receiver/drier

Discharge
(High)
pressure
gauge
abnormally
low
After turning off air conditioning,
high and low pressure gauge
balanced quickly
•
Compressor seal defective
• Poor compression due to
defective compressor
gasket •
Replace or repair
compressor
Low pressure gauge is lowered
after condenser is cooled by
water
•
Excessive refrigerant in
system

•
Discharge and
recover refrigerant
Recharge to specified
amount
Low pressure hose temperature
around the compressor refrigerant
line connector is lower than
around evaporator

•
Unsatisfactory valve
operation due to defective
temperature sensor of
expansion valve
• Expansion valve opens too
long •
Replace the
expansion valve




After turning off air conditioning,
high and low pressure gauge is
balanced quickly •
Compressor gasket is
defective
•
Replace


Suction
(Low)
pressure
gauge
abnormally
high
Air conditioning turns off before
passenger compartment is
sufficiently
cool •
Electronic thermostat
defective
•
Check the electronic
thermostat and
replace as necessary


* For the charging and discharging operations in the table above, refer to “RECOVERY, RECYCLING,
EVACUATION AND CHARGING” in this section.

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ISUZU KB P190 2007