YH4
GRAND
VITARA
1B-6 AIR CONDITIONING (OPTIONAL)
DIAGNOSIS
GENERAL
ConditionPossible CauseCorrection
Cool air won't come out
(A / C system won't
operative)No refrigerant
Fuse blown
A / C switch faulty
Blower motor switch faulty
A / C thermistor faulty
Dual pressure switch faulty
Wiring or grounding faulty
A / C ON permission signal in ECM
faulty
A / C controller and its circuit faultyRecover, evacuation and charging.
Check ªIG METERº fuse, ªREAR DEFGº
fuse, and ªA / C FUSEº and check for
short circuit to ground.
Check A / C switch.
Check blower motor switch.
Check A / C evaporator thermistor.
Check dual pressure switch.
Repair as necessary.
Check ON permission signal.
Check A / C controller and its circuit.
Cool air won't come out
(A / C compressor won't
operative)Magnet clutch faulty
Compressor relay faulty
Compressor thermal switch faulty
(if equipped)
Drive belt loose or broken
Compressor faulty
A / C ON permission signal in ECM
faulty
A / C controller faultyCheck magnet clutch.
Check compressor thermal switch.
Check compressor relay.
Adjust or replace drive belt.
Check compressor.
Check ON permission signal.
Check A / C controller.
Cool air won't come out
(A / C condenser cooling
fan motor won't
operative)Condenser cooling fan relay faulty
Wiring or grounding faulty
ªA / C condenser cooling fan relayº
signal in ECM faulty
Condenser cooling fan motor faultyCheck condenser cooling fan relay.
Repair as necessary.
Check A / C condenser cooling fan relay
signal.
Check condenser cooling fan motor.
Cool air won't come out
(Blower motor won't
operative)Fuse blown
Blower motor relay faulty
Blower motor resistor faulty
Blower motor switch faulty
Wiring or grounding faulty
Blower motor faultyCheck ªHEATER FUSEº, ªREAR DEFGº
fuse and check for short circuit to
ground.
Check blower motor relay.
Check blower motor resistor.
Check blower motor switch.
Repair as necessary.
Check blower motor.
Cool air won't come out
or insufficient cooling
(A / C system normal
operative)Insufficient or excessive charge of
refrigerant
Refrigerant leak in system
Condenser clogged
A / C evaporator clogged or frosted
A / C thermistor faulty
A / C controller faulty
Expansion valve faulty
Drive belt slipping
Magnetic clutch faultyCheck charge of refrigerant.
Check system for leaks.
Check condenser.
Check A / C evaporator.
Check A / C thermistor.
Check A / C controller.
Check expansion valve.
Check or replace drive belt.
Check magnetic clutch.
YH4
GRAND
VITARA
AIR CONDITIONING (OPTIONAL) 1B-7
ConditionPossible CauseCorrection
Cool air does not come
out or insufficient
cooling (A / C system
normal operative)Compressor faulty
Air in A / C system
Air leaking from cooling unit or air
duct
Heater and ventilation system faulty
Blower motor faulty
Excessive compressor oil existing in
A / C systemCheck compressor.
Replace condenser dryer, and
evacuation and charging.
Repair as necessary.
Check blower unit.
Check heater control lever assembly.
Check heater assembly.
Check blower motor.
Pull out compressor oil in A / C system
circuit, and replace compressor.
Cool air does not comes
out only intermittentlyWiring connection faulty
Expansion valve faulty
Excessive moisture in A / C system
A / C controller faulty
Magnetic clutch faulty
Excessive charge of refrigerantRepair as necessary.
Check expansion valve.
Replace condenser dryer, and
evacuation and charging.
Check A / C controller.
Check magnetic clutch.
Check charge of refrigerant.
Cool air comes out only
at high speedsCondenser clogged
Insufficient charge of refrigerant
Air in A / C system
Drive belt slipping
Compressor faultyCheck condenser.
Check charge of refrigerant.
Replace condenser dryer, and
evacuation and charging.
Adjust or replace drive belt.
Check compressor.
Cool air does not comes
out only at high speedsExcessive charge of refrigerant
A / C evaporator frostedCheck charge refrigerant.
Check A / C evaporator.
Check A / C thermistor.
Insufficient velocity of
cooled airA / C evaporator clogged or frosted
Air leaking from cooling unit or air
duct
Blower motor faulty
Wiring or grounding faultyCheck A / C evaporator.
Repair as necessary.
Check blower motor.
Repair as necessary.
YH4
GRAND
VITARA
1B-8 AIR CONDITIONING (OPTIONAL)
DIAGNOSIS OF ABNORMAL NOISE
There are various types of noise, ranging from those produced in the engine compartment to those from the pas-
senger compartment, also from rumbling noises to whistling noises.
ABNORMAL NOISE FROM COMPRESSOR
ConditionPossible CauseCorrection
During compressor operation, a
rumbling noise is heard
proportional to engine
revolutions.Inadequate clearance in piston
area (piston or swash-plate).Repair or replace compressor as
necessary.
A loud noise is heard at a certain
rpm, disproportionately to engine
revolution.Loose or faulty V-belt.
Loose mounting bolts.Adjust V-belt tension, or
replace belt.
Retighten mounting bolts.
A loud rattle is heard at low
engine rpm.Loose compressor center bolt.Retighten center bolt.
Replace compressor if it was
operated in this condition for a
long time.
ABNORMAL NOISE FROM MAGNETIC CLUTCH
ConditionPossible CauseCorrection
A rumbling noise is heard when
compressor is not operating.Worn or damaged bearings.Replace bearings.
A chattering noise is heard when
compressor is engaged.Faulty clutch gap (excessive).
Worn clutch friction surface.
Compressor oil leaked from shaft
seal, contaminating the friction
surface.Adjust clutch gap.
Replace clutch.
Replace compressor shaft oil
seal.
ABNORMAL NOISE FROM TUBING
ConditionPossible CauseCorrection
A droning noise is heard inside
vehicle, but not particularly
noticeable in engine
compartment.Faulty tubing clamps.
Resonance caused by pulsation
from variations in refrigerant
pressure.Reposition clamps or increase
the number of clamps.
Attach a silencer to tubing, or
modify its position and length.
ABNORMAL NOISE FROM CONDENSER
ConditionPossible CauseCorrection
Considerable vibration in
condenser.Resonance from condenser
mounting stay and body.Firmly insert a silencer between
condenser mounting stay and
body.
YH4
GRAND
VITARA
AIR CONDITIONING (OPTIONAL) 1B-11
COMPRESSION SYSTEM DIAGNOSIS
Compressor troubles are mainly following three types: gas leakage, noise and insufficient pressure.
Compressor gas leakages in most cases develop from the shaft seal. When detecting gas leakage, always use
a leak tester. If a small amount of oil seeps out from the shaft seal, there is no necessity of replacing the seal. The
shaft seal has been designed to allow a small amount of oil to leak out for lubricating purpose. Thus, the shaft seal
should be replaced only when a large amount of compressor oil is leaking out or when gas leakage is discovered
by using gas tester.
In regard to noise and insufficient pressure, repairs should be made only after diagnosing the trouble properly.
CONDITION
POSSIBLE CAUSESCORRECTION
Noise from compressorDefective bearing
Defective cylinder and / or shaftReplace.
Replace.
Noise from magnetic clutchDefective bearing
Defective clutch faceReplace.
Replace.
Insufficient coolingDefective gasketReplace.
Defective reed valveReplace.
Not rotatingLocked compressor
Seized magnetic clutch
Rotating parts seized by insufficient oil
amountReplace.
Replace.
Replace.
Oil and / or gas leakageDefective seal
Defective O-ringReplace.
Replace.
YH4
GRAND
VITARA
1B-20 AIR CONDITIONING (OPTIONAL)
A / C CONTROLLER VOLTAGE VALUES TABLE
TerminalWireCircuitMeasurement
groundNormal valueCondition
AC1-1B/WController main
power supplyGround to
engine (Fig. B)10 ± 14 voltsIgnition switch ON with engine
stopped
AC1-2B/YController main
groundGround to body
(Fig. A)± 0.4 ± 0 voltEngine running
AC1 4Or
Refrigerant
p
ressure switchGround to
0 ± 1 volt
Refrigerant pressure within 225 kPa
(2.3 kg / cm
2, 32.7 psi) to 2548 kPa
(26 kg / cm
2, 370 psi) with engine
running
AC1-4Orpressure switch
inputengine (Fig. B)
10 ± 14 volts
Refrigerant pressure below
196 kPa (2.0 kg / cm
2, 28 psi) or
above 3140 kPa (32 kg / cm
2, 455 psi)
with engine running
AC1 7G/B
A / C switch input
and / or defroster
Ground to
8 ± 14 volts
Blower fan motor switch and A / C or
defroster position switch (see NOTE)
ON with engine running
AC1-7G/Bposition switch
input (see NOTE)engine (Fig. B)
0 ± 1.5 volts
Blower fan motor switch or A / C or
defroster position switch (see NOTE)
OFF with engine running
AC1 9Gr/W
Signal input from
ECM (A / C ON
Ground to10 ± 14 voltsApprove of A / C ON
AC1-9Gr/W(
permission
signal)engine (Fig. B)0 ± 1 voltA / C ON forbid
AC1-13Y/B
Signal output to
ECM (A / C ON
request signal)Ground to engine
(Fig. B)0 ± 1.5 volts
Blower fan motor switch and A / C or
defroster position switch (see NOTE)
ON with engine running at evaporator
thermistor temperature input more
than approx. 2.5C (less than 2.5 V
(5840 )) and refrigerant pressure
switch is ON
10 ± 14 voltsExcept the above-mentioned with
engine running
AC1-16P
Compressor
magnet clutch
relay outputGround to engine
(Fig. B)0 ± 1 volt
Blower fan motor switch and A / C or
defroster position switch ON with
engine running at evaporator
thermistor temperature input more
than approx. 2.5C (less than 2.5 V
(5840 )), refrigerant pressure
switch ON and signal input from ECM
ON
10 ± 14 voltsExcept the above-mentioned with
engine running
YH4
GRAND
VITARA
1. Evaporator thermistorTemperature
Resistance ( )
AIR CONDITIONING (OPTIONAL) 1B-43
A / C EVAPORATOR THERMISTOR
(EVAPORATOR TEMPERATURE SENSOR)
A thermistor is a temperature sensor to sense the temperature of
air discharged from evaporator. The electrical characteristic is
shown in the figure.
When temperature is lower than preset temperature, amplifier
makes magnet clutch turn off to prevent evaporator from frosting.
INSPECTION
Check resistance between A / C evaporator thermistor (1) termi-
nals.
If check results are as not specified, replace thermistor.
Sensor Temperature
Resistance
0C, 32F7.0 ± 7.7 k
25C, 77F2.1 ± 2.4 k
REMOVAL
Refer to ªCOOLING UNIT (EVAPORATOR)º in this section.
INSTALLATION
1) Reverse removal sequence to install thermistor.
2) Enable air bag system. Refer to ªENABLING AIR BAG SYS-
TEMº in Section 10B.
3) Evacuate and charge system. Refer to ªEVACUATINGº and
ªCHARGINGº in this section.
YH4
GRAND
VITARA
1B-50 AIR CONDITIONING (OPTIONAL)
REMOVAL
1) Run engine at idle with A / C ON for 10 minutes.
2) Disconnect negative (±) cable at battery.
3) Recover refrigerant from refrigeration system using recovery
and recycling equipment.
NOTE:
The amount of compressor oil at removed must be mea-
sured and the same amount must be poured when installing
the compressor.
4) Disconnect thermal protector lead wire.
5) Disconnect suction and discharge hoses from compressor as-
sembly.
NOTE:
Cap open fitting immediately to keep moisture out of sys-
tem.
6)For G16 engine:
Remove compressor drive belt by loosening compressor as-
sembly mounting bolts.
For J20 engine:
Remove generator belt. Refer to Section 6H.
For H25 engine:
Remove compressor drive belt by loosening tension pulley bolt.
7) Remove compressor with magnet clutch assembly from its
mount.
8) If compressor assembly is replaced. Drain oil from compressor
assembly, and measure its amount.
YH4
GRAND
VITARA
AIR CONDITIONING (OPTIONAL) 1B-53
1. Clutch plate bolt
2. Clutch plate
3. Circlip
4. Clutch pulley
5. Shim
6. Clutch coil
7. Compressor 567
MAGNET CLUTCH ASSEMBLY (FOR DENSO)
INSPECTION
Inspect clutch plate and clutch pulley for signs of oil.
Check clutch pulley for noise and grease leakage.
Using an ohmmeter, measure resistance of clutch coil between
clutch lead wire (1) and compressor body (2).
If measured resistance is not within tolerance, replace magnet
clutch assembly.
Standard resistance: 3.5 ± 5.0 at 20C, 68F
REMOVAL
1) Remove compressor assembly from vehicle. Refer to ªCOM-
PRESSOR ASSEMBLYº in this section.
2) Fix clutch plate (1) with special tool (A) and remove clutch plate
bolt.
Special Tool
(A): 09991-06020
NOTE:
Do not reuse clutch plate bolt.
3) Using special tool (B), remove clutch plate (1).
Special Tool
(B): 09991-06030