2004 ISUZU TF SERIES Workshop Manual

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Page 3089 of 4264

ISUZU TF SERIES 2004 Workshop Manual HEATER AND AIR CONDITIONING 1-79

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

Page 3090 of 4264

ISUZU TF SERIES 2004 Workshop Manual 1-80 HEATER AND AIR CONDITIONING

BLOWER MOTOR DOES NOT RUN

Replace
YES
Is No.SBF-8 (30A) slow blow fuse OK?
Is heater & A/C relay (X-11) OK?
YES
Is resistor OK?
YES
Is fan c

Page 3091 of 4264

ISUZU TF SERIES 2004 Workshop Manual HEATER AND AIR CONDITIONING 1-81

BLOWER MOTOR DOES NOT RUN IN CERTAIN POSITION

A 1: (Low)
Blower motor does no
tB 2: (Medium Low) Position
run at
C 3: (Medium Hi)

D 4: (High)
* Checkin

Page 3092 of 4264

ISUZU TF SERIES 2004 Workshop Manual 1-82 HEATER AND AIR CONDITIONING

BLOWER MOTOR DOES NOT STOP AT “OFF” POSITION

Is fan control knob (Fan switch) OK?
YES
Short circuit between chassis side connector terminal
No.
C10

Page 3093 of 4264

ISUZU TF SERIES 2004 Workshop Manual HEATER AND AIR CONDITIONING 1-83

AIR CONDITIONING CYCLE TROUBLESHOOTING

TROUBLE POSSIBLE CAUSE CORRECTION
No cooling or
insufficient
cooling
1. Magnetic clutch does not run

Refer to �

Page 3094 of 4264

ISUZU TF SERIES 2004 Workshop Manual 1-84 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

Page 3095 of 4264

ISUZU TF SERIES 2004 Workshop Manual HEATER AND AIR CONDITIONING 1-85

RESULT SYMPTOM TROUBLE CAUSE CORRECTION
Discharge
(High)
pressure
gauge
abnormally
high Reduced or no air flow through
the condenser

Condenser clogged o

HEATER AND AIR CONDITIONING 1-85

RESULT SYMPTOM TROUBLE CAUSE CORRECTION
Discharge
(High)
pressure
gauge
abnormally
high 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
After stopping air conditioning,
pressure drops approx. 196 kPa
(2.0kg/cm
2 / 28 PSI) quickly
Air in system

Evacuate and charge
refrigerant system
Discharge
(High)
pressure
gauge
abnormally
low 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

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
Suction
(Low)
pressure
gauge
abnormally
high 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

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.

Page 3096 of 4264

ISUZU TF SERIES 2004 Workshop Manual 1-86 HEATER AND AIR CONDITIONING

RESULT SYMPTOM TROUBLE CAUSE CORRECTION
Suction
(Low)
pres-sure
abnormally
low
Condenser is not hot and
excessive bubble in sight glass

Insuf

1-86 HEATER AND AIR CONDITIONING

RESULT SYMPTOM TROUBLE CAUSE CORRECTION
Suction
(Low)
pres-sure
abnormally
low
Condenser is not hot and
excessive bubble in sight glass

Insufficient refrigerant

Check sight
glass.(See “Reading
Sight Glass”)

Check for leaks

Discharge and
recover refrigerant.
Recharge to specified
amount
Frost on the expansion valve inlet
line
Expansion valve clogged

Replace the
expansion valve

A distinct difference in
temperature between the inlet and
outlet refrigerant lines of the
receiver/drier
Receiver/drier clogged

Replace the receiver/
drier

Expansion valve outlet refrigerant
line is not cold and low-pressure
gauge indicates vacuum

The temperature sensor of
the expansion valve is
defective, and the valve
cannot regulate the correct
flow of the refrigerant
Replace the
expansion valve

Discharge temperature is low and
air flow from vents is restricted
Frozen evaporator core fins

Check electronic
thermostat and
replace as necessary
Low-pressure gauge reading is
low, or a vacuum reading may be
shown
Clogged or blocked
refrigerant line

Replace refrigerant
line
Suction
(Low) and
Discharge
(High)
pressure
abnor-
mally
high
No bubbles in sight glass after
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
Reduce air flow through con-
denser

Condenser clogged
Radiator (condenser) fan
does not rotate properly
Clean
Check cooling fan
operation
Suction (Low) pressure hose is
not cold
Air in system
Evacuate and charge
refrigerant
Suction
(Low) and
Discharge
(High)
pres-sure
abnor-
mally
low
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

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