2008 SUZUKI SWIFT engine symptom diagnosis

Downloaded from www.Manualslib.com manuals search engine 6C-8 Power Assisted Steering System:
Step 2: DTC Check, Record and Clearance
First, check DTC, referring to “DTC Check”. If DTC is
indicated, print it or write them down and then clear them
by referring to “DTC Clearance”. DTC indicates
malfunction that occurred in the system but does not
indicate whether it exists now or it occurred in the past
and the normal condition has been restored now. To
check which case applies, check the symptom in
question according to Step 5 and recheck DTC
according to Step 6 and 7.
Attempt to diagnose a trouble based on DTC in this step
only or failure to clear the DTC in this step will lead to
incorrect diagnosis, trouble diagnosis of a normal circuit
or difficulty in troubleshooting.
Step 3 and 4: Visual Inspection
As a preliminary step, be sure to perform visual check of
the items that support proper function of the P/S system
referring to “Visual Inspection”.
Step 5: Trouble Symptom Confirmation
Based on information obtained in “Step 1: Customer
Complaint Analysis: ” and “S tep 2: DTC Check, Record
and Clearance: ”, confirm trouble symptoms. Also,
reconfirm trouble symptom by performing test drive and
turning steering wheel fully to right and left at stopped
vehicle.
Step 6 and 7: Rechecking and Record of DTC
Refer to “DTC Check” for checking procedure.
Step 8: Steering Symptom Diagnosis and P/S
System Symptom Diagnosis
Perform basic steering system check according to
“Steering Symptom Diagnosis in Section 6A” first. When
the end of the flow has been reached, check the parts of
the system suspected as a possible cause referring to
“P/S System Symptom Diagnosis” and based on
symptoms appearing on the vehicle (symptoms obtained
through steps of customer complaint analysis, trouble
symptom confirmation and/or basic P/S system check)
and repair or replace faulty parts, if any.
Step 9: Troubleshooting for DTC (See each DTC
Diag. Flow)
Based on the DTC indicated in Step 6 or 7 and referring
to the applicable DTC diag. flow, locate the cause of the
trouble, namely in a sensor, switch, wire harness,
connector, actuator, P/S control module or other part and
repair or replace faulty parts.
Step 10: Intermittent Problems Check
Check parts where an intermittent trouble is easy to
occur (e.g., wire harness, connector, etc.), referring to
“Intermittent and Poor Connection Inspection in Section
00” and related circuit of DTC recorded in Step 2. Step 11: Final Confirmation Test
Confirm that the problem symptom has gone and the P/
S system is free from any abnormal conditions. If what
has been repaired is related to the DTC, clear the DTC
once, perform DTC confirmation procedure and confirm
that no DTC is indicated.
“EPS” Warning Light CheckS7RS0B6304002
1) Turn ignition switch to ON position (without engine
running) and chec k if the “EPS” warning light (1)
lights up. If the light dose not light up, go to ““EPS”
Warning Light Does Not Come ON with Ignition
Switch Turned ON before Engine Starts” of the
diagnostic flows.
2) Start engine and check if the “EPS” warning light turns OFF. If light remains ON and no DTC is stored
in P/S control module, go to ““EPS” Warning Light
Remains ON Steady after Engine Starts” for
troubleshooting.
DTC CheckS7RS0B6304003
1) Turn ignition switch to OFF position.
2) Connect SUZUKI scan tool to data link connector (DLC) (1) located on underside of instrument panel
at driver’s seat side.
Special tool
(A): SUZUKI scan tool
1
I6RS0C630002-01
(A)
1
I4RS0B450003-01

Downloaded from www.Manualslib.com manuals search engine 6C-12 Power Assisted Steering System:
Scan Tool Data Definitions
Battery Voltage
This parameter indicates battery positive voltage.
TQS Power Supply (Torque Sensor Power Supply, V)
This parameter indicates the power supply voltage which
the P/S control module supplies to the torque sensor.
TQS Main Torque (Torque Sensor Main Torque, N ⋅m)
The torque sensor is installed to detect the steering force
and the steering directio n. It consists of two
potentiometers and the main torque sensor is one of
these.
TQS Sub Torque (Torque Sensor Sub Torque, N ⋅m)
The torque sensor is installed to detect the steering force
and the steering directio n. It consists of two
potentiometers and the sub-torque sensor is one of
these. Its output characteristics are compared with those
of the main torque sensor.
Assist Torque (N ⋅m)
This parameter is an internal parameter of the P/S
control module. It is obtained by computing the torque
sensor input signal. Motor Control (Motor Control Current, A)
Based on the input signal, the P/S control module
determines the assist amount
and controls the current to
the motor suitable for that a ssist amount. This parameter
indicates that control value.
Motor Monitor (Motor Monitor Current, A)
This parameter indicates the actually measured value of
the current flowing to the motor. The motor circuit
condition is diagnosed by co mparing this parameter with
“Motor Control” parameter described previously.
Vehicle Speed (km/h, MPH)
Vehicle speed signal is fed from BCM. P/S control
module determines the amount of power assist based on
this vehicle speed signal and the torque sensor signal.
Engine Speed (rpm)
Engine speed signal is fed from the ECM so that it can
be used for trouble diagnos is of the electric power
steering system.
Motor Volt (V)
This parameter indicates the voltage between motor
terminals.
Ignition switch (ON, OFF)
This parameter indicates the condition of the power
supply through the ignition switch.
Visual InspectionS7RS0B6304007
Visually check the following pats and system.
P/S System Symptom DiagnosisS7RS0B6304008
This section describes trouble diagnosis of the P/S system parts whose trouble is not indicated by the on-board
diagnostic system (self-diagnostic functi on). When no malfunction is indicated by the on-board diagnostic system
(self-diagnosis function) and those stee ring basic parts as described in “Steering Symptom Diagnosis in Section 6A”
are all in good condition, check the following power steer ing system parts which may be a possible cause for each
symptom of the steering. Inspection Item Referring section
Battery Level, leakage, color “Batte ry Description in Section 1J”
Connectors of electric wire
harness Disconnection friction “Intermittent and Poor
Connection Inspection in Section 00”
Fuses Burning “Cautions in Body Electric al System Servicing in Section 9A”
Parts Installation, damage
Other parts that can be checked visually
Condition Possible cause Correction / Reference Item
Steering wheel feels
heavy (Perform “Steering
Force Check” before
diagnosis.) Steering wheel installed improperly
(twisted)
Install steering wheel correctly.
Poor performance of torque sensor Check torque sensor referring to “Torque
Sensor and Its Circuit Inspection”.
Poor performance of P/S motor Check motor referring to “P/S Motor and Its
Circuit Inspection”.
Steering gear case assembly faulty Replace.
Poor performance of vehicle speed
signal from ECM Check vehicle speed signal circuit referring to
“DTC C1121 / C1123 / C1124: VSS Circuit
Failure”.

Downloaded from www.Manualslib.com manuals search engine Table of Contents 7- i
7
Section 7
CONTENTS
HVAC
Precautions ................................................. 7-1
Precautions............................................................. 7-1
Precautions on HVAC ........................................... 7-1
Heater and Ventilation.... ......................... 7A-1
General Description ............................................. 7A-1
Heater and Ventilation Construction ................... 7A-1
Schematic and Routing Diagram ........................ 7A-2 Heater and Ventilation Wiring Circuit Diagram .... 7A-2
Diagnostic Information and Procedures ............ 7A-3 Heater and Ventilation Symptom Diagnosis........ 7A-3
Repair Instructions .............................................. 7A-4 HVAC Unit Components ..................................... 7A-4
HVAC Unit Removal and Installation .................. 7A-4
Blower Motor Removal and Installation............... 7A-4
Blower Motor Inspection ..................................... 7A-4
Blower Motor Resistor Removal and Installation ......................................................... 7A-5
Blower Motor Resistor Inspection ....................... 7A-5
Blower Motor Relay Inspection ........................... 7A-6
HVAC Control Unit Components ......................... 7A-6
HVAC Control Unit Remova l and Installation ...... 7A-7
Blower Speed Selector In spection ...................... 7A-9
Air Intake Selector Inspec tion ............................. 7A-9
Air Intake Control Actuator Removal and Installation ......................................................... 7A-9
Air Intake Control Actuator Inspection .............. 7A-10
Center Ventilation Louver Removal and Installation ....................................................... 7A-10
Side Ventilation Louver Removal and Installation ....................................................... 7A-11
HVAC Air Filter Removal and Installation (If Equipped)........................................................ 7A-12
HVAC Air Filter Inspection (If Equipped) ........... 7A-12
Air Conditioning System... ...................... 7B-1
Manual Type ............................................................ 7B-1
Precautions........................................................... 7B-1A/C System Caution ............................................ 7B-1
Precautions on Servicing A/C System ................ 7B-1
General Description ............................................. 7B-3 Refrigerant Type Identifica tion ............................ 7B-3
Sub-Cool A/C System Description ...................... 7B-4
A/C Operation Description .................................. 7B-4 Schematic and Routing Diagram ........................7B-5
Major Components of A/C System ...................... 7B-5
A/C System Wiring Diagram ............................... 7B-6
Diagnostic Information and Procedures ............7B-7 A/C System Symptom Diagnosis ........................ 7B-7
Abnormal Noise Sympto m Diagnosis of A/C
System .............................................................. 7B-9
A/C System Performance Inspection ................ 7B-10
A/C System Inspection at ECM ......................... 7B-15
Repair Instructions ........... .................................7B-16
Operation Procedure for Re frigerant Charge .... 7B-16
Condenser Assembly On-Vehicle Inspection .... 7B-21
Condenser Assembly Removal and Installation ....................................................... 7B-21
Receiver/Dryer Removal and Installation .......... 7B-22
HVAC Unit Components ................................... 7B-23
HVAC Unit Removal and In stallation ................ 7B-24
Evaporator Inspection ....................................... 7B-24
Evaporator Thermistor (Evaporator Temperature Sensor) Removal and
Installation ....................................................... 7B-25
Evaporator Thermistor (Evaporator Temperature Sensor) Inspec tion..................... 7B-25
Expansion Valve Removal and Installation ....... 7B-26
Expansion Valve Inspection .............................. 7B-26
A/C Refrigerant Pressure Sensor and Its Circuit Inspection............................................. 7B-26
A/C Refrigerant Pressu re Sensor Removal
and Installation ................................................ 7B-26
A/C Switch Inspection ....................................... 7B-27
Compressor Relay Inspection ........................... 7B-27
Compressor Drive Belt Inspection and Adjustment ...................................................... 7B-27
Compressor Drive Belt Removal and Installation ....................................................... 7B-28
Compressor Assembly Removal and Installation ....................................................... 7B-28
Compressor Assembly Components................. 7B-29
Magnet Clutch Inspection.................................. 7B-29
Magnet Clutch Removal and Installation........... 7B-29
Relief Valve Inspection...................................... 7B-31
Relief Valve Removal and Installation............... 7B-32
Specifications .................... .................................7B-32
Tightening Torque Specifications ...................... 7B-32
Special Tools and Equipmen t ...........................7B-33

Downloaded from www.Manualslib.com manuals search engine 7-ii Table of Contents
Recommended Service Material ....................... 7B-33
Special Tool ...................................................... 7B-33
Automatic Type .................... .................................7B-34
Precautions.........................................................7B-34 A/C System Caution .......................................... 7B-34
Precautions in Diagnosing Trouble ................... 7B-34
Precautions on Servicing A/C System .............. 7B-34
General Description .......... .................................7B-34
Auto A/C System Descript ion ............................ 7B-34
HVAC Control Module Operation Description ... 7B-36
Refrigerant Type Identifica tion .......................... 7B-36
Sub-Cool A/C System Description .................... 7B-36
A/C Operation Description ................................ 7B-36
On-Board Diagnostic System Description ......... 7B-37
Schematic and Routing Diagram ......................7B-37 Major Components of A/C System .................... 7B-37
A/C System Wiring Diagra m ............................. 7B-38
Diagnostic Information and Procedures ..........7B-39 A/C System Symptom Diagnosis ...................... 7B-39
Abnormal Noise Sympto m Diagnosis of A/C
System ............................................................ 7B-42
DTC Check........................................................ 7B-42
DTC Clearance ................................................. 7B-43
DTC Table ......................................................... 7B-44
Fail-Safe Table ................. ................................. 7B-45
Scan Tool Data ................................................. 7B-46
Air Conditioning System Check......................... 7B-47
Visual Inspection ............................................... 7B-49
DTC B1502: Inside Air Temperature Sensor and/or Its Circuit Malfunction .......................... 7B-49
DTC B1503: A/C Evaporator Air Temperature Sensor and/or Its Circuit Malfunction .............. 7B-50
DTC B1504: Sunload Sensor and/or Its Circuit Malfunction ......... ................................. 7B-52
DTC B1511: Temperature Control Actuator (Position Sensor) and/or Its Circuit
Malfunction ...................................................... 7B-53
DTC B1512: Air flow Control Actuator (Position Sensor) and/or Its Circuit
Malfunction ...................................................... 7B-55
DTC B1513: Temperature Control Actuator and/or Its Circuit Malfunction .......................... 7B-57
DTC B1514: Air Flow Co ntrol Actuator and/or
Its Circuit Malfunction ...................................... 7B-60
DTC B1541: HVAC Control Module Back-Up Power Supply Malfunction .............................. 7B-62
DTC B1546: A/C Refrigerant Pressure Malfunction ...................................................... 7B-63
DTC B1551: Serial Communication Circuit Malfunction ...................................................... 7B-63
DTC B1552: Serial Communication Signal Malfunction ...................................................... 7B-64
DTC B1553: CAN Communication Signal Malfunction ...................................................... 7B-65
DTC B1557: Vehicle Speed Sensor Signal Malfunction ...................................................... 7B-65
DTC B1561: Engine Coolant Temperature Sensor Signal Malfunctio n .............................. 7B-66 DTC B1562: Outside Air Temperature Sensor
Signal Malfunction ........................................... 7B-66
DTC B1563: A/C Refr igerant Pressure
Sensor Signal Malfunction .............................. 7B-66
Inspection of HVAC Control Module and Its Circuit .............................................................. 7B-67
A/C System Performance Inspection ................ 7B-70
A/C System Inspection at ECM ......................... 7B-70
Repair Instructions ............ ................................7B-71
Operation Procedure for Refrigerant Charge .... 7B-71
HVAC Unit Components ................................... 7B-72
HVAC Unit Removal and In stallation ................ 7B-73
Temperature Control Actuator Removal and Installation ....................................................... 7B-73
Temperature Control Actuat or Inspection ......... 7B-73
Air Flow Control Actuator Removal and Installation ....................................................... 7B-74
Air Flow Control Actuator Inspection ................. 7B-74
Air Intake Control Actuator Removal and Installation ....................................................... 7B-75
Air Intake Control Actuator Inspection............... 7B-75
Actuator Linkage Inspection .............................. 7B-76
Blower Motor Controller Removal and Installation ....................................................... 7B-76
Blower Motor Controller Inspection ................... 7B-76
HVAC Control Module Removal and Installation ....................................................... 7B-77
Sunload Sensor Removal and Installation ........ 7B-77
Sunload Sensor Inspection ............................... 7B-77
Outside Air Temperature Sensor Removal and Installation ................................................ 7B-77
Outside Air Temperature Sensor Inspection ..... 7B-77
Inside Air Temperature Sensor Removal and Installation ....................................................... 7B-78
Inside Air Temperature Sens or Inspection ........ 7B-78
Condenser Assembly On-Vehicle Inspection .... 7B-78
Condenser Assembly Removal and Installation ....................................................... 7B-78
Receiver/Dryer Removal and Installation .......... 7B-78
Evaporator Inspection ....................................... 7B-78
Evaporator Temperature Sensor Removal and Installation ................................................ 7B-78
Evaporator Temperature Se nsor Inspection ..... 7B-78
Expansion Valve Removal an d Installation ....... 7B-78
Expansion Valve Inspection .............................. 7B-78
A/C Refrigerant Pressure Sensor and Its Circuit Inspection............................................. 7B-78
A/C Refrigerant Pressu re Sensor Removal
and Installation ................................................ 7B-78
Compressor Relay Inspection .
.......................... 7B-78
Compressor Drive Belt Inspection and Adjustment ...................................................... 7B-78
Compressor Drive Belt Removal and Installation ....................................................... 7B-79
Compressor Assembly Removal and Installation ....................................................... 7B-79
Compressor Assembly Components................. 7B-79
Magnet Clutch Removal and Installation........... 7B-79
Magnet Clutch Inspection.................................. 7B-79
Relief Valve Inspection...................................... 7B-79

Downloaded from www.Manualslib.com manuals search engine Heater and Ventilation: 7A-3
Diagnostic Information and Procedures
Heater and Ventilation Symptom DiagnosisS7RS0B7104001
ConditionPossible cause Correction / Reference Item
Blower motor does not
operate with blower
speed selector ON Fuse blown
Check related fuses, and then check for short
circuit to ground.
Blower motor relay faulty Check blower motor relay referring to “Blower
Motor Relay Inspection”.
Blower motor resistor faulty Check blower motor resistor referring to
“Blower Motor Resistor Inspection”.
Blower speed selector faulty Check blower speed selector referring to
“Blower Speed Selector Inspection”.
Blower motor faulty Check blower motor referring to “Blower Motor
Inspection”.
Wiring or grounding faulty Repair as necessary.
Incorrect temperature
output Temperature control cable broken or
bent (manual A/C) Check temperature control cable.
Temperature control lever faulty (manual
A/C) Check temperature control lever.
Incorrect installation of temperature
control cable (manual A/C) Check position and adjust it as necessary.
Temperature control door assembly
broken Repair temperature control door assembly.
Air ducts clogged Repair air ducts.
Heater core leaked or clogged Replace heater core.
Heater hoses leaked or clogged Replace heater hoses.
Thermostat faulty Check thermostat referring to “Thermostat
Inspection in Section 1F”.
Temperature control actuator faulty
(automatic A/C) Check temperature control actuator referring to
“Temperature Control Actuator Inspection in
Section 7B”.
HVAC control module faulty (automatic
A/C) Check HVAC control module referring to
“Inspection of HVAC Control Module and Its
Circuit in Section 7B”.
Wiring or grounding faulty (automatic A/
C) Repair as necessary.
Air outlet port does not
change or does not agree
with air flow selector’s
position even if air flow
selector is changed Air flow control cable broken or bent
(manual A/C)
Check air flow control cable.
Air flow control lever faulty (manual A/C) Check air flow control lever.
Incorrect installation of air flow control
cable (manual A/C) Check position and adjust it as necessary.
Air flow control door assembly broken Repair air flow control door assembly.
Air ducts leaked or clogged Repair air ducts.
Air flow control actuator faulty
(automatic A/C) Check air flow control actuator referring to “Air
Flow Control Actuator
Inspection in Section
7B”.
HVAC control module faulty (automatic
A/C) Check HVAC control module referring to
“Inspection of HVAC Control Module and Its
Circuit in Section 7B”.
Wiring or grounding faulty (automatic A/
C) Repair as necessary.
Air intake door does not
change even if air intake
mode is changed Air intake door broken
Repair air intake door.
Air intake control actuator faulty Check air intake control actuator referring to
“Air Intake Control Actuator Inspection”.
Air intake selector faulty Check air intake selector referring to “Air Intake
Selector Inspection”.
Wiring or grounding faulty Repair as necessary.

Downloaded from www.Manualslib.com manuals search engine Air Conditioning System: Manual Type 7B-7
Diagnostic Information and Procedures
A/C System Symptom DiagnosisS7RS0B7214001
ConditionPossible cause Correction / Reference Item
No cool air comes out (A/
C system does not
operate) No refrigerant
Perform recovery, evacuation and charge
referring to “Operation Procedure for
Refrigerant Charge”.
Fuse blown Check related fuses, and then check for short
circuit to ground.
A/C switch faulty Check A/C switch referring to “A/C Switch
Inspection”.
Blower speed selector faulty Check blower speed selector referring to
“Blower Speed Selector Inspection in Section
7A”.
Evaporator thermistor (Evaporator
temperature sensor) faulty Check evaporator thermistor (evaporator
temperature sensor) referring to “Evaporator
Thermistor (Evaporator Temperature Sensor)
Inspection”.
A/C refrigerant pressure sensor faulty Check A/C refrigerant pressure sensor
referring to “A/C Refrigerant Pressure Sensor
and Its Circuit Inspection”.
Wiring or grounding faulty Repair as necessary.
ECM faulty Check ECM referring to “A/C System
Inspection at ECM”.
Magnet clutch faulty Check magnet clutch referring to “Magnet
Clutch Inspection”.
Compressor drive belt loosened or
broken Adjust or replace drive belt.
Compressor faulty Check compressor.
Compressor relay faulty Check compressor relay referring to
“Compressor Relay Inspection”.
BCM faulty Check BCM referring to “Inspection of BCM
and its Circuits in Section 10B”.
No cool air comes out
(radiator cooling fan
motor does not operate) Fuse blown
Check related fuses, and then check for short
circuit to ground.
Wiring or grounding faulty Repair as necessary.
Radiator cooling fan motor relay faulty Check radiator cooling fan motor relay
referring to “Radiator Cooling Fan Relay
Inspection in Section 1F”.
Radiator cooling fan motor faulty Check radiator cooling fan motor referring to
“Radiator Cooling Fan Removal and
Installation in Section 1F”.
ECM and/or its circuit faulty Check ECM and/or its circuit referring to “A/C
System Inspection at ECM”.
No cool air comes out
(blower motor does not
operate) Fuse blown
Check related fuses, and then check for short
circuit to ground.
Blower motor relay faulty Check blower motor relay referring to “Blower
Motor Relay Inspection in Section 7A”.
Blower motor resistor faulty Check blower motor resistor referring to
“Blower Motor Resistor Inspection in Section
7A”.
Blower speed selector faulty Check blower speed selector referring to
“Blower Speed Selector Inspection in Section
7A”.
Wiring or grounding faulty Repair as necessary.
Blower motor faulty Check blower motor referring to “Blower Motor
Inspection in Section 7A”.

Downloaded from www.Manualslib.com manuals search engine Air Conditioning System: Manual Type 7B-9
Abnormal Noise Symptom Diagnosis of A/C SystemS7RS0B7214002
Abnormal Noise from Compressor
Abnormal Noise from Magnetic Clutch
Abnormal Noise from Tubing
Abnormal Noise from Condenser Assembly
Abnormal Noise from Crankshaft PulleyInsufficient airflow of
cooled air
A/C evaporator clogged or frosted
Check A/C evaporator and evaporator
thermistor (evaporator temperature sensor)
referring to “Evaporator Inspection” and
“Evaporator Thermistor (Evaporator
Temperature Sensor) Inspection”.
Air leaking from HVAC unit or air duct Repair as necessary.
Blower motor faulty Check blower motor referring to “Blower Motor
Inspection in Section 7A”.
Wiring or grounding faulty Repair as necessary.
Condition Possible cause Correction / Reference Item
Condition
Possible cause Correction / Reference Item
During compressor
operation, a rumbling
noise is heard
proportional to engine
revolutions Inadequate clearance in scroll area
Replace compressor.
A loud noise is heard at a
certain rpm,
disproportionately to
engine revolution Loose or faulty compressor drive belt
Adjust drive belt tension or replace drive belt.
Loose compressor mounting bolts Retighten mounting bolts.
A loud rattle is heard at
low engine rpm Loose compressor clutch plate bolt
Retighten clutch plate bolt.
Replace compressor if it was operated in this
condition for a long time.
Condition Possible cause Correction / Reference Item
A rumbling noise is heard
when compressor is not
in operation Worn or damaged bearings
Replace magnet clutch assembly.
A chattering noise is
heard when compressor
is in operation Faulty magnet clutch clearance
(excessive clearance)
Adjust magnet clutch clearance.
Worn magnet clutch friction surface Replace magnet clutch assembly.
Compressor oil leaked from shaft seal,
contaminating the friction surface Replace compressor body assembly.
Condition
Possible cause Correction / Reference Item
A droning noise is heard
from inside of the vehicle,
but not particularly
noticeable in engine
compartment Faulty tubing clamps
Reposition clamps or increase the number of
clamps.
Resonance caused by pulsation from
variations in re frigerant pressure Attach a silencer to tubing, or modify its
position and length.
Condition
Possible cause Correction / Reference Item
Considerable vibration in
condenser assembly Resonance from condenser assembly
bracket and body Firmly insert a silenc
er between condenser
assembly bracket and body.
Condition Possible cause Correction / Reference Item
A large rattling noise is
heard at idle or sudden
acceleration Loosen crankshaft pulley bolt
Retighten bolt.

Downloaded from www.Manualslib.com manuals search engine 7B-12 Air Conditioning System: Manual Type
High pressure gauge
Low pressure gaugeCondition Possible cause Correction
Pressure is higher than
acceptable range
(“A” area) Refrigerant overcharged Recharge.
Expansion valve frozen or clogged Check expansion valve.
Clogged refrigerant passage of high pressure side Clean or replace.
Radiator cooling fan malfunction
(Insufficient cooling of condenser)
Check radiator cooling fan.
Dirty or bent condenser fins
(Insufficient cooling of condenser) Clean or repair.
Compressor malfunction (Insuffi cient oil etc.) Check compressor.
Engine overheat Check engine cooling system
referring to “Engin
e Cooling Symptom
Diagnosis in Section 1F”.
Pressure is lower than
acceptable range
(“B” area) Insufficient refrigerant
(Insufficient charge or leakage)
Check for leakage, repair if necessary
and recharge.
Expansion valve malfunction
(valve opens too wide) Check expansion valve.
Compressor malfunction
(Insufficient compression) Check compressor.
Condition Possible cause Correction
Pressure is higher than
acceptable range
(“C” area) Expansion valve malfunction
(valve opens too wide)
Check expansion valve.
Compressor malfunction
(Insufficient compression) Check compressor.
Pressure is lower than
acceptable range
(“D” area) Insufficient refrigerant
(Insufficient charge or leakage)
Check for leakage, repair if necessary
and recharge.
Expansion valve malfunction
(valve opens too narrow) Check expansion valve.
Clogged refrigerant passage (crashed pipe) Repair or replace.