2002 ISUZU AXIOM Service Repair Manual

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
1A±23
Air Conditioning Parts
852R200008
Legend
(1) Liquid Line (High-Pressure Pipe)
(2) Clip
(3) Discharge Line (High-Pressure Hose)
(4) Pressure Switch
(5) Receiver/Drier(6) Condenser Air Guide
(7) Condenser & Receiver Tank Assembly
(8) Condenser Fan
(9) Compressor
(10) Suction Line (Low-Pressure Hose)
(11) Evaporator Assembly

1A±24
HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
Diagnosis
Air Conditioning Cycle Diagnosis
ConditionPossible causeCorrection
No cooling or insufficient cooling.Magnetic clutch does not run.Refer to ªMagnetic Clutch Diagnosisº
in this section.
Compressor is not rotating properly.
Drive belt is loose or broken.Adjust the drive belt to the specified
tension or replace the drive belt.
Compressor is not rotating properly.
Magnetic clutch face is not clean and
slips.Clean the magnetic clutch face or
replace.
Compressor is not rotating properly.
Incorrect clearance between
magnetic drive plate and pulley.Adjust the clearance. Refer to
Compressor in this section.
Compressor is not rotating properly.
Compressor oil leaks from the shaft
seal or shell.Replace the compressor
Compressor is not rotating properly.
Compressor is seized.Replace the compressor
Insufficient or excessive charge of
refrigerant.Discharge and recover the
refrigerant. Recharge to the
specified amount.
Leaks in the refrigerant system.Check the refrigerant system for
leaks and repair as necessary.
Discharge and recover the
refrigerant. Recharge to the
specified amount.
Condenser is clogged or insufficient
radiation.Clean the condenser or replace as
necessary.
Temperature control link unit of the
heat unit is defective.Repair the link unit.
Unsteady operation due to a foreign
substance in the expansion valve.Replace the expansion valve.
Poor operation of the electronic
thermostat.Check the electronic thermostat and
replace as necessary.
Insufficient velocity of cooling air.Evaporator clogged or frosted.Check the evaporator core and
replace or clean the core.
Air leaking from the cooling unit or air
duct.Check the evaporator and duct
connection, then repair as
necessary.
Blower motor does not rotate
properly.Refer to Fan Control Lever (Fan
Switch) Diagnosis in this section.
*For the execution of the charging and discharging
operation in the table above, refer to
Recovery,
Recycling, Evacuating and Charging in this section.

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
1A±25
Checking The Refrigerant System With Manifold Gauge
Since Refrigerant-134a (HFC-134a) is used in the air
conditioning system in this vehicle, be sure to use
manifold gauges, charging hoses and other air
conditioning service tools for HFC-134a when
checking the refrigerant system.
Conditions:

Run the engine at idle

Air conditioning switch is ªONº

Run the blower motor at ªHIGHº position (5 positions)

Temperature control set to ªMAX COLDº (65
F)

Air source selector at ªCIRCº

Open the engine hood

Close all the doors
Normal Pressure:

At ambient temperature: approx. 25±30
C
(77±86
F).

At low-pressure side: approx. 147.1±294.2 kPa
(21.3±42.7 psi).

At high-pressure side: approx. 1372.9±1863.3 kPa
(199.1±270.2 psi).
Refer to the table on the refrigerant pressure-temperature
relationship.
HFC-134a Pressure-Temperature Relationship
PressureTemperature
(kPa)(psi)(
C)(
F)
365.3±20±4.4
679.7±155
10415±1014
14721±523
19628032
25537541
314451050
392571559
471682068
569822577
677983086
78511 43595
91213240104
10591544511 3
121617650122

1A±26
HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
Connect The Manifold Gauge
Low-pressure hose (LOW) Ð Suction side
High pressure hose (HI) Ð Discharge side
901R100020
Legend
(1) Low Side
(2) High Side

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
1A±27
ConditionPossible causeCorrection
Discharge (High Gauge) Pressure
Abnormally High
Condenser clogged or dirty.Clean the condenser fins
Abnormally HighCooling fan does not operate
properly.Check the cooling fan operation.
Discharge (High Gauge) Pressure
Abnormally High.
Insufficient cooling.Excessive refrigerant in system.Discharge and recover refrigerant.
Recharge to specified amount.
Discharge (High Gauge) Pressure
Abnormally High.
High pressure gauge drop. (After
stopping A/C, the pressure drops
approx. 196 kPa (28 psi) quickly)Air in system.Evacuate and charge refrigerant
system.
Discharge (High Gauge) Pressure
Abnormally Low.
Insufficient coolingInsufficient refrigerant in system.Check for leaks. Discharge and
recover the refrigerant. Recharge to
the specified amount.
Discharge (High Gauge) Pressure
Abnormally Low.
Low pressure gauge indicates
vacuum.Clogged or defective expansion
valve.Replace the expansion valve.
Discharge (High Gauge) Pressure
Abnormally Low.
Frost or dew on refrigerant line
before and after the receiver/drier or
expansion valve, and low pressure
gauge indicates vacuum.Restriction caused by debris or
moisture in the receiver/drier.Check system for restriction and
replace the receiver/drier.
Discharge (High Gauge) Pressure
Abnormally Low.Compressor seal defectiveRepair or replace the compressor.
High and low pressure gauge
balanced quickly. (After turned off
A/C)Poor compression due to a defective
compressor gasket.Repair or replace the compressor.
Suction (Low Gauge) Pressure
Abnormally High.
Low pressure gauge (Low pressure
gauge is lowered after condenser is
cooled by water.)Excessive refrigerant in system.Discharge and recover refrigerant
Recharge to specified amount.
Suction (Low Gauge) Pressure
Abnormally High.
Low pressure hose temperature.
(Low pressure hose temperature
around the compressor refrigerant
Unsatisfactory valve operation due
to defective temperature sensor of
expansion valve.Replace the expansion valve.
around the com ressor refrigerant
line connector is lower than around
evaporator.)Expansion valve opens too long.Replace the expansion valve.
Suction (Low Gauge) Pressure
Abnormally High.
High and low pressure gauge
balanced quickly. (After turned off
A/C)Compressor gasket is defective.Repair or replace the compressor.
Suction (Low Gauge) Pressure
Abnormally Low.
Insufficient cooling.Insufficient refrigerant in system.Check for leaks. Discharge and
recover the refrigerant. Recharge to
specified amount.
Suction (Low Gauge) Pressure
Abnormally Low.
Frost on the expansion valve inlet
lineExpansion valve clogged.Replace the expansion valve.

1A±28
HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
Condition CorrectionPossible cause
Suction (Low Gauge) Pressure
Abnormally Low
Receiver/drier inlet and outlet
refrigerant line temperature. (A
distinct difference in temperature
develops.)Receiver/Drier clogged.Replace the receiver/drier.
Suction (Low Gauge) Pressure
Abnormally Low.
Expansion valve outlet refrigerant
line. (Not cold and low pressure
gauge indicates vacuum.)Expansion valve temperature sensor
is defective.Replace the expansion valve.
Suction (Low Gauge) Pressure
Abnormally Low.
When the refrigerant line is clogged
or blocked, the low pressure gauge
reading will decrease, or a vacuum
reading may be shown.Clogged or blocked refrigerant line.Replace refrigerant line.
Suction (Low Gauge) Pressure
Abnormally Low.
Evaporator core is frozen.Thermo switch defective.Replace thermo switch.
Suction (Low Gauge) and Discharge
(High Gauge) Pressure Abnormally
High.Excessive refrigerant in system.Discharge and recover the
refrigerant, the Recharge to the
specified amount.
Insufficient cooling.Condenser clogged or dirty.Clean the condenser fin.
Suction (Low Gauge) and Discharge
(High Gauge) Pressure Abnormally
High.
Suction (Low) pressure hose (Not
cold).Air in system.Evacuate and charge refrigerant.
Suction (Low Gauge) and Discharge
(High Gauge) Pressure Abnormally
Low.
Insufficient coolingInsufficient refrigerant in system.Check for leaks. Discharge and
recover refrigerant. Recharge to
specified amount.
A/C Ð Air Conditioning

HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
1A±29
Condenser Fan Diagnosis
While the air conditioning is ON, the cycling switch in the
triple pressure switch senses the refrigerant pressure,
and activates the condenser fan to improve the cooling
capacity of the condenser when the refrigerant pressure
exceeds a set pressure value. The condenser fan stops
when the air conditioning is turned ªOFFº or when the
pressure goes down below the set pressure value.
D08R200041
ConditionPossible causeCorrection
Condenser fan does not run.±Refer to ªChart Aº.
±Refer to ªChart Bº.

1A±30
HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
Chart ªAº Condenser Fan Does Not Run
StepActionYe sNo
1Are 30A fuse normal?Go to Step 2Replace
2Is relay (X-16) normal?Go to Step 3Replace
3Is pressure switch normal?
Go to Step 4
Switch defective
or insufficient
refrigerant.
4Is fan motor normal?Go to Step 5Replace
51. Disconnect condenser fan relay (X-16).
2. Check to see if battery voltage is present at the chassis side
relay terminal NO. X16-5.
Is there a battery voltage?
Go to Step 6
Repair open
circuit between
Condenser Fan
fuse (30A) and
No.X16-5.
61. Reconnect condenser fan relay (X-16).
2. Check to see if battery voltage is present at chassis side
connector terminal No.C21-3.
Is there a battery voltage?
Go to Step 7
Repair open
circuit between
fuse (10A) and
C21-3.
7Check to see if continuity between chassis side relay terminal
No.X16-2 and the chassis side connector terminal No.C21-4.
Is there a continuity?
Go to Step 8
Repair open
circuit.
8Check to see if continuity between chassis side connector
terminal No. C16-1 and chassis side relay terminal No.X16-1.
Is there a continuity?Poor ground or
open circuit
between chassis
side connector
terminal
No.X16-4 (or
No.C16-2) and
body ground
(No.C10).
Repair open
circuit.
Chart ªBº Condenser Fan Does Not Stop
StepActionYe sNo
11. Disconnect the triple pressure connector.
Does condenser fan stop?
Replace the triple
pressure switch.
Replace the
condenser fan
relay.