Page 555 of 1500
ENGINE AND TRANSMISSION
CONFIGURATION DIAGRAMS80-6
ENGINE AND TRANSMISSIONM1801000401079
B-01 (2-GR) INJECTOR 1
B-02 (3-B) MANIFOLD ABSOLUTE PRESSURE
SENSOR
B-03 (2-GR) INJECTOR 3
B-04 (2-GR) INJECTOR 5
B-05 (2-B) EVAPORATIVE EMISSION PURGE
SOLENOID
B-06 (6-B) THROTTLE BODY ASSEMBLY
B-07 (2-GR) BRAKE FLUID LEVEL SWITCHB-08 (4-GR) RIGHT BANK HEATED OXYGEN
SENSOR (REAR)
B-09 (4-B) RIGHT BANK HEATED OXYGEN
SENSOR (FRONT)
B-10 (5) MASS AIRFLOW SENSOR
B-16X (4) A/T CONTROL RELAY
B-17X (4) MPI RELAY
B-18X (4) A/C COMPRESSOR CLUTCH RELAY
Page 559 of 1500
Page 592 of 1500

CENTRALISED JUNCTION
CIRCUIT DIAGRAMS90-15
NO. POWER SUPPLY
CIRCUITNAME RATED
CAPACITY (A)HOUSING
COLOURLOAD CIRCUIT
1 Fusible link No.1 Fuse 30 Green Rear window demister
2 30 Green Blower motor and resistor
3
4
5 15 Blue Accessory socket
6 15 Blue Data link connector and ETACS-ECU
7 Ignition switch (ACC) 15 Blue ETACS-ECU
8
9 Ignition switch (IG2) 7.5 Brown Sunroof assembly
10 Ignition switch (ACC) 7.5 Brown Remote controlled mirror
11
12
13 Ignition switch (IG1) 7.5 Brown Fuel pump relay and Engine ECU
14 Ignition switch (ACC) 20 Yellow Windscreen wiper
15 Fusible link No.1
(Fuse No.5 in junction
block)7.5 Brown Remote controlled mirror
16 Ignition switch (IG2) 7.5 Brown A/C compressor clutch relay,
A/C-ECU, blower relay, condenser
fan motor, fan control relay,
front-ECU, outside/inside air selection
damper control motor and rear
window defogger relay
17 Ignition switch (IG1)
18 7.5 Brown A/T control relay, input shaft speed
sensor, output shaft speed sensor,
Engine ECU, rear combination lamp
and SRS-ECU
19 7.5 Brown ABS-ECU, ABS/TCL-ECU, column
switch, combination meter,
ETACS-ECU, multi-center display unit
and SRS-ECU
20 10 Red Ignition coil
21
22
23 Fusible link No.5 20 Yellow Sunroof assembly
24
Page 594 of 1500
CENTRALISED JUNCTION
CIRCUIT DIAGRAMS90-17
CENTRALISED RELAY
NOTE: The triangle mark on the relay housing should face that on the relay box.CONNECTOR NO. NAME CONNECTOR NO. NAME
A-05X Fog lamp relay A-16X
A-06X Horn relay B-11X
A-07XB-12X
A-08XB-13X
A-09XB-14X
A-10X Fan control relay B-15X
A-11X Front-ECU B-16X A/T control relay
A-12X Front-ECU B-17X
MPI relay
A-15X
B-18X A/C compressor clutch relay
Page 702 of 1500

HEATER, AIR CONDITIONING AND VENTILATION55-1
GROUP 55
HEATER, AIR
CONDITIONING AND
VENTILATION
CONTENTS
GENERAL DESCRIPTION. . . . . . . . .55-3
AUTO A/C DIAGNOSIS . . . . . . . . . . .55-5
INTRODUCTION. . . . . . . . . . . . . . . . . . . . . 55-5
AUTOMATIC AIR CONDITIONING
TROUBLESHOOTING STRATEGY . . . . . . 55-5
DIAGNOSTIC FUNCTION . . . . . . . . . . . . . 55-5
DIAGNOSTIC TROUBLE CODE CHART . 55-9
DIAGNOSTIC TROUBLE CODE
PROCEDURES . . . . . . . . . . . . . . . . . . . . . . 55-10
SYMPTOM CHART . . . . . . . . . . . . . . . . . . 55-68
SYMPTOM PROCEDURES . . . . . . . . . . . . 55-69
DATA LIST REFERENCE TABLE . . . . . . . 55-133
ACTUATOR TEST REFERENCE . . . . . . . . 55-136
CHECK AT A/C-ECU TERMINAL . . . . . . . . 55-137
SPECIAL TOOLS . . . . . . . . . . . . . . . .55-139
ON-VEHICLE SERVICE . . . . . . . . . . .55-141
REFRIGERANT LEVEL TEST . . . . . . . . . . 55-141
A/C COMPRESSOR CLUTCH TEST . . . . . 55-141
SIMPLE INSPECTION OF THE A/C
PRESSURE SENSOR . . . . . . . . . . . . . . . . 55-141
COMPRESSOR DRIVE BELT
ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . 55-142
CHARGING . . . . . . . . . . . . . . . . . . . . . . . . . 55-142
PERFORMANCE TEST . . . . . . . . . . . . . . . 55-143
REFRIGERANT LEAK INSPECTION
PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . 55-144A/C NOISE TEST . . . . . . . . . . . . . . . . . . . . 55-146
POWER RELAY CHECK . . . . . . . . . . . . . . . 55-148
IDLE-UP OPERATION CHECK . . . . . . . . . . 55-149
HEATER CONTROL ASSEMBLY AND
A/C SWITCH . . . . . . . . . . . . . . . . . . . .55-150
REMOVAL AND INSTALLATION . . . . . . . . 55-150
HEATER UNIT, HEATER CORE,
BLOWER ASSEMBLY AND
EVAPORATOR UNIT . . . . . . . . . . . . .55-151
REMOVAL AND INSTALLATION . . . . . . . . 55-151
REMOVAL AND INSTALLATION . . . . . . . . 55-153
DISASSEMBLY AND ASSEMBLY . . . . . . . 55-154
INSPECTION. . . . . . . . . . . . . . . . . . . . . . . . 55-155
BLOWER ASSEMBLY DISASSEMBLY
AND ASSEMBLY . . . . . . . . . . . . . . . . . . . . . 55-156
MOTORS AND TRANSISTOR . . . . . .55-157
REMOVAL AND INSTALLATION . . . . . . . . 55-157
INSPECTION. . . . . . . . . . . . . . . . . . . . . . . . 55-158
SENSORS . . . . . . . . . . . . . . . . . . . . . .55-160
REMOVAL AND INSTALLATION . . . . . . . . 55-160
INSPECTION. . . . . . . . . . . . . . . . . . . . . . . . 55-161
Continued on next page
Page 705 of 1500

GENERAL DESCRIPTION
HEATER, AIR CONDITIONING AND VENTILATION55-4
OPERATION
.
CONDENSER FAN AND RADIATOR FAN
CONTROL
The ECU judges the required revolution speed of
radiator fan motor and condenser fan motor using
the input signals transmitted from A/C switch, output
shaft speed sensor and engine coolant temperature
sensor. The ECU activates the fan control relays to
drive the radiator fan motor and condenser fan
motor.
.
COMPRESSOR CONTROL
When operating the air conditioning switch
The air thermo sensor, which senses the temper-
ature of the air flowing out of the evaporator,
deactivates the compressor at 3
C (37.4F) or
below.
The dual pressure switch turns OFF when the
refrigerant pressure becomes excessively high or
low, thus protecting the compressor circuit (See
Table below).
When the air thermo sensor is activated, and the
ignition switch, blower switch, and air condition-
ing switch are ON, the A/C compressor clutch
relay is energized.
When operating the mode selection dial
The air conditioning will work when the mode
selection dial is set to the "Defroster" or
"Defroster/foot" position, or the temperature con-
trol dial is set to the "MAX A/C" position. In other
dial positions, when the air conditioning switch is
turned on, the air conditioning will work.
A/C Compressor Clutch Relay ON Conditions
Ignition switch (IG2) ONNOTE: A/C compressor clutch relay is
de-energized when any one switch, sensor
or control unit shown on the left turns off.
NOTE: The components marked by
*
communicate with the ECU. If the air thermo
sensor detects a temperature of 3
C
(37.4
F), the A/C-ECU will turn off the A/C
compressor clutch relay. Blower switch ON
Air conditioning switch, mode selection dial
defroster, defroster/foot position or temperature
control MAX A/CON
Air thermo sensor*
Pressure detected
by A/C pressure
sensor2940 kPa or less (If the
refrigerant pressure exceeds
2940 kPa, A/C compressor
clutch relay is not ON
condition until the refrigerant
pressure has been measured
up to 2350 kPa or less.)ON
190 kPa or more (If the
refrigerant pressure falls short
of 190 kPa, A/C compressor
clutch relay is not ON
condition until the refrigerant
pressure has been measured
up to 220 kPa or more.)
A/C compressor clutch relay driving transistor (within
ecu)ON
Page 776 of 1500
AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-75
INSPECTION PROCEDURE 4: When the A/C is Operating, Temperature Inside the Passenger
Compartment does not Decrease (Cool Air is not Emitted).
.
TECHNICAL DESCRIPTION (COMMENT)
If cool air is not distributed when the A/C switch is on,
the A/C compressor relay system may be defective.
.
TROUBLESHOOTING HINTS
Improper amount of refrigerant
Malfunction of the air thermo sensor
Malfunction of the ambient air temperature sen-
sor
Malfunction of the A/C pressure sensor
Malfunction of the A/C compressor relay
Malfunction of the A/C refrigerant temperature
switch
Malfunction of the air conditioning compressor
clutch
Malfunction of the A/C-ECU
Malfunction of the ECU
Damaged harness wires or connectors
Refer to component locations GROUP-70
Refer to configuration diagrams GROUP-80
Refer to circuit diagrams GROUP-90
DIAGNOSIS
Required Special Tools:
MB991223: Harness Set
: Scan Tool (MUT-III Sub Assembly)
Page 778 of 1500
AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-77
STEP 5. Check A/C compressor clutch relay connector
B-18X for loose, corroded or damaged terminals, or
terminals pushed back in the connector.
Q: Is A/C compressor clutch relay connector B-18X in
good condition?
YES : Go to Step 6.
NO : Repair or replace the connector. Refer to GROUP
00E, Harness Connector Inspection P.00E-2. Check
that the air conditioning works normally.
STEP 6. Check the A/C compressor clutch relay continuity.
Follow the table below to check the A/C compressor clutch
relay for continuity.
Q: Is the A/C compressor clutch relay in good condition?
YES : Go to Step 7.
NO : Replace the A/C compressor clutch relay. Check that
the air conditioning works normally.
BATTERY
VOLTAGETESTER
CONNECTIONSPECIFIED
CONDITION
Not applied 1
4 Open circuit
Connect
terminal 2 to the
positive battery
terminal
Connect
terminal 3 to the
negative battery
terminal1
4 Less than 2 ohms