1B-2 AIR CONDITIONING (OPTIONAL)
REMOVING MANIFOLD GAUGE SET ...... 1B-26
LEAK TEST................................................ 1B-26
LIQUID LEAK DETECTORS .................. 1B-26
ON-VEHICLE SERVICE ................................ 1B-27
SERVICE PRECAUTION........................... 1B-27
REFRIGERANT LINE ............................ 1B-27
HANDLING REFRIGERANT HFC-134a
(R-134a) ................................................. 1B-28
REFRIGERANT RECOVERY ................ 1B-28
REFRIGERANT CHARGE ..................... 1B-28
CONDENSER ASSEMBLY........................ 1B-28
RECEIVER/DRYER ................................... 1B-30
RADIATOR/CONDENSER COOLING FAN
MOTOR...................................................... 1B-31COOLING UNIT (EVAPORATOR) ............ 1B-32
A/C EVAPORATOR TEMPERATURE
SENSOR.................................................... 1B-34
EXPANSION VALVE ................................. 1B-34
A/C REFRIGERANT PRESSURE
SWITCH..................................................... 1B-35
A/C SWITCH.............................................. 1B-36
RADIATOR/CONDENSER COOLING FAN
MOTOR RELAY No.1, No.2 and No.3 ....... 1B-36
COMPRESSOR ......................................... 1B-36
MAGNET CLUTCH .................................... 1B-38
LIP TYPE SEAL ......................................... 1B-41
REQUIRED SERVICE MATERIAL ............... 1B-43
SPECIAL TOOL ............................................ 1B-44
AIR CONDITIONING (OPTIONAL) 1B-3
GENERAL DESCRIPTION
REFRIGERANT CIRCULATION
REFRIGERANT TYPE
Whether the A/C in the vehicle being serviced uses HFC-134a
(R-134a) or CFC-12 (R-12) is indicated on compressor label (1).
Also, it can be checked by the shape of the service (charge) valve
(2).
1. Compressor 4. Receiver/dryer 7. Evaporator
2. Magnet clutch 5. A/C refrigerant pressure switch
3. Condenser assembly 6. Expansion valve
AIR CONDITIONING (OPTIONAL) 1B-5
DIAGNOSIS
GENERAL DIAGNOSIS TABLE
Condition Possible Cause Correction
Cool air won’t come
out (A/C system won’t
operative)No refrigerant Perform recover, evacuation and charging.
Fuse blown Check fuses in circuit fuse and main fuse
boxes, and check short circuit to ground.
A/C switch faulty Check A/C switch.
Blower fan switch faulty Check blower fan switch referring to Sec-
tion 1A.
A/C evaporator temperature sensor
faultyCheck A/C evaporator temperature sen-
sor.
A/C refrigerant pressure switch faulty Check A/C refrigerant pressure switch.
Wiring or grounding faulty Repair as necessary.
ECT sensor faulty Check ECT sensor referring to Section
6E1.
ECM and its circuit faulty Check ECM and its circuit referring to Sec-
tion 6E1.
Cool air won’t come
out (A/C compressor
won’t operative)ECM faulty Check ECM and its circuit referring to Sec-
tion 6E1.
Magnet clutch faulty Check magnet clutch.
Compressor drive belt loosen or broken Adjust or replace drive belt.
Compressor faulty Check compressor.
Compressor thermal switch faulty Check compressor thermal switch
Cool air won’t come
out (A/C condenser
cooling fan motor
won’t operative)Fuse blown Check fuses in circuit fuse and main fuse
boxes, and check short circuit to ground.
Wiring or grounding faulty Repair as necessary.
Radiator/condenser cooling fan motor
relay faultyCheck radiator/condenser cooling fan
motor relay No.1, No.2 and No.3.
Radiator/condenser cooling fan motor
faultyCheck radiator/condenser cooling fan
motor.
ECM faulty Check ECM and its circuit referring to Sec-
tion 6E1.
Cool air won’t come
out (Blower fan motor
won’t operative)Fuse blown Check “HTR” fuse in circuit fuse box and
main fuses, and check short circuit to
ground.
Blower fan motor resistor faulty Check blower fan motor resistor to Section
1A.
Blower fan switch faulty Check blower fan switch referring to Sec-
tion 1A.
Wiring or grounding faulty Repair as necessary.
Blower fan motor faulty Check blower fan motor referring to Sec-
tion 1A.
1B-6 AIR CONDITIONING (OPTIONAL)
Cool air won’t come
out or insufficient
cooling (A/C system
normal operative)Insufficient or excessive charge of
refrigerantCheck charge of refrigerant and system for
leaks.
Condenser clogged Check condenser.
A/C evaporator clogged or frosted Check A/C evaporator and A/C evaporator
temperature sensor.
A/C evaporator temperature sensor
faultyCheck A/C evaporator temperature sen-
sor.
Expansion valve faulty Check expansion valve.
Receiver/dryer clogged Check receiver/dryer.
Compressor drive belt loosen or broken Adjust or replace drive belt.
Magnetic clutch faulty Check magnetic clutch.
Compressor faulty Check compressor.
Air in A/C system Replace dryer, and perform evacuation
and charging.
Air leaking from cooling unit or air duct Repair as necessary.
Heater and ventilation system faulty Check air inlet box (cooling unit), heater
control assembly and heater unit referring
to Section 1A.
Blower fan motor faulty Check blower fan motor referring to Sec-
tion 1A.
Excessive compressor oil existing in A/
C systemPull out compressor oil in A/C system cir-
cuit, and check compressor.
Cool air won’t come
out only intermittentlyWiring connection faulty Repair as necessary.
Expansion valve faulty Check expansion valve.
Excessive moisture in A/C system Replace dryer, and perform evacuation
and charging.
Magnetic clutch faulty Check magnetic clutch.
Excessive charge of refrigerant Check charge of refrigerant.
Cool air comes out
only at high speedCondenser clogged Check condenser.
Insufficient charge of refrigerant Check charge of refrigerant.
Air in A/C system Replace dryer, and perform evacuation
and charging.
Compressor drive belt loosen or broken Adjust or replace drive belt.
Compressor faulty Check compressor.
Cool air won’t come
out only at high speedExcessive charge of refrigerant Check charge of refrigerant.
A/C evaporator frosted Check A/C evaporator and A/C evaporator
temperature sensor.
Insufficient velocity of
cooled airA/C evaporator clogged or frosted Check A/C evaporator and A/C evaporator
temperature sensor.
Air leaking from cooling unit or air duct Repair as necessary.
Blower fan motor faulty Check blower fan motor referring to Sec-
tion 1A.
Wiring or grounding faulty Repair as necessary. Condition Possible Cause Correction
AIR CONDITIONING (OPTIONAL) 1B-7
ABNORMAL NOISE DIAGNOSIS
There are various types of noise, ranging from those produced in the engine compartment to those from the
passenger compartment, also from rumbling noises to whistling noises.
ABNORMAL NOISE FROM COMPRESSOR
ABNORMAL NOISE FROM MAGNETIC CLUTCH
ABNORMAL NOISE FROM TUBING
ABNORMAL NOISE FROM CONDENSER
Condition Possible Cause Correction
During compressor
operation, a rumbling
noise is heard propor-
tional 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, dis-
proportionately 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 oper-
ated in this condition for a long
time.
Condition Possible Cause Correction
A rumbling noise is
heard when compres-
sor is not operating.Worn or damaged bearings Replace magnet clutch assembly.
A chattering noise is
heard when compres-
sor is engaged.Faulty clutch clearance (excessive) Adjust clutch clearance.
Worn clutch friction surface Replace magnet clutch assembly.
Compressor oil leaked from lip type seal, con-
taminating the friction surfaceReplace compressor body assem-
bly.
Condition Possible Cause Correction
A droning noise is
heard inside 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 refrigerant pressureAttach a silencer to tubing, or mod-
ify its position and length.
Condition Possible Cause Correction
Considerable vibra-
tion in condenser.Resonance from condenser bracket and body Firmly insert a silencer between
condenser bracket and body.
AIR CONDITIONING (OPTIONAL) 1B-19
ECM Voltage Values Table for Relation of A/C Control
Terminal Wire Circuit Measurement
groundNormal value Condition
C41-1 PNK/BLK Compressor magnet
clutch outputGround to engine
(Fig B)12 – 15 V Except the above-mentioned condition with engine
running
0 – 1 V Blower fan switch and A/C switch ON with engine
running
C41-5 BLK/RED Main power supply for
ECMGround to engine
(Fig B)10 – 14 V Ignition switch ON with engine stopped
C41-6 BLK/RED Main power supply for
ECMGround to engine
(Fig B)10 – 14 V Ignition switch ON with engine stopped
C41-10 BRN/
WHTMain relay drive Ground to engine
(Fig B)0.5 – 1.2 V Ignition switch ON with engine stopped
10 – 14 V Ignition switch OFF
C41-16 YEL/GRN A/C switch input Ground to engine
(Fig B)12 – 15 V Blower fan switch or A/C switch OFF with engine
running
0 – 1 V Blower fan switch and A/C switch ON with engine
running
C41-18 BLU Radiator/condenser
cooling fan relay out-
put 1Ground to engine
(Fig B)0 – 1 V Blower fan switch and A/C switch ON
Engine coolant temperature at more than 97.5°C
(207.5°F) with engine running
12 – 15 V Blower fan motor switch or A/C switch OFF
Engine coolant temperature at less than 97.5°C
(207.5°F) with engine running
C42-1 BLK/ORN Main ground for ECM Ground to body
(Fig A)–0.5 – 1 V Engine running
C42-2 BLK ECM ground for
power circuitGround to body
(Fig A)–0.5 – 1 V Engine running
C42-3 BLK/ORN ECM ground for
power circuitGround to body
(Fig A)–0.5 – 1 V Engine running
C42-10 ORN Sensor ground for
ECT sensorGround to body
(Fig A)–0.5 – 1 V Engine running
C42-14 LT GRN/
BLKECT sensor input Ground to engine
(Fig B)0.71 – 0.75 V
(298 – 320 Ω
)Engine coolant temperature at approximately 80°C
(176°F) with engine running
0.35 – 0.37 V
(135 – 144 Ω
)Engine coolant temperature at Approximately
110°C (230°F) with engine running
If the temperature is more than 114°C (232°F),
compressor and condenser cooling fan should be
stop (come back at less than 112°C (230°F))
C42-18 PNK/GRN Medium pressure
switch inputGround to engine
(Fig B)–0.5 – 1 V Medium pressure switch of A/C refrigerant pres-
sure switch ON
12 – 15 V Medium pressure switch of A/C refrigerant pres-
sure switch OFF
G02-3 PPL/YEL Radiator/Condenser
cooling fan relay out-
put 2Ground to engine
(Fig B)0 – 1 V Blower fan motor switch ON, A/C switch ON and
medium pressure switch OFF
Engine coolant temperature at more than 102.5°C
(216.5°F) with engine running
12 – 15 V Blower fan motor switch OFF, A/C switch OFF or
medium pressure switch ON
Engine coolant temperature at less than 102.5°C
(216.5°F) with engine running
G02-10 ORN Sensor ground for A/C
evaporator tempera-
ture sensorGround to engine
(Fig A)–0.5 – 1 V Engine running
G02-13 PNK/BLU Blower fan speed
inputGround to engine
(Fig B)0 – 1 V Blower fan motor switch “ML”, “MH”, or “H” with
engine running
4 – 7 V Blower fan motor switch “L” position with engine
running
12 – 15 V Blower fan motor switch OFF with engine running
G02-14 WHT/BLK A/C evaporator tem-
perature sensor inputGround to engine
(Fig B)2.09 – 2.17 V
(1940 – 2060 Ω
)A/C evaporator temperature at approximately 25°C
(77°F) with engine running
3.52 – 3.59 V
(6450 – 6850 Ω
)A/C evaporator temperature at approximately 0°C
(32°F) with engine running
If the temperature is less than approximately 2.5°C
(36.5°F), compressor and condenser cooling fan
should be stop (come back at more than approxi-
mately 4°C (39.2°F)
AIR CONDITIONING (OPTIONAL) 1B-37
6) Remove compressor drive belt (1) by loosening tension pul-
ley nut (2) and adjusting bolt (3).
7) Disconnect magnet clutch lead wire coupler.
8) Disconnect suction pipe (4) and discharge hose (5) from
compressor (6).
9) Remove compressor mounting bolts (7), and then remove
compressor (6) from its bracket.
INSTALLATION
Reverse removal procedure to install compressor noting the fol-
lowing instructions.
If compressor is replaced, pour new compressor oil by refer-
ring to “REPLENISHING COMPRESSOR OIL” in this sec-
tion.
Evacuate and charge system by referring to “RECOVERY”
in this section.
Adjust drive belt tension by referring to “COMPRESSOR
DRIVE BELT” in this section. NOTE:
Cap open fittings immediately to keep moisture out of
system.
1B-38 AIR CONDITIONING (OPTIONAL)
MAGNET CLUTCH
INSPECTION
Check clutch plate and clutch pulley for wear and oil soaked
conditions respectively.
Check clutch pulley bearing for noise, wear and grease leak-
age.
Measure clutch coil for resistance at 20°C (68°F).
If the measured resistance does not remain within tolerance,
replace magnet clutch assembly.
Clutch coil resistance
: 3.4 – 4.1
Ω
ΩΩ Ω
1. Compressor thermal switch 6. Clutch coil a. Front head bolt
: Tighten bolt (a) first, and next (b)
2. Compressor body 7. Clutch pulley b. Front head bolt
: Tighten bolt (a) first, and next (b)
3. O-ring 8. Circlip c. Clutch plate bolt
4. Lip type seal 9. Circlip Tightening torque
5. Front head 10. Clutch plate Do not reuse.