Page 57 of 2870
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
AC
Page
1. Basic Diagnostics Procedure ......................................................................2
2. General Description ....................................................................................3
3. Electrical Component Location ...................................................................5
4. Auto A/C Control Module I/O Signal............................................................7
5. Diagnostic Chart for Self-Diagnosis ............................................................9
6. Diagnostics for A/C System Malfunction ...................................................12
7. Diagnostic Procedure for Actuators ..........................................................21
8. Diagnostic Procedure for Sensors ............................................................32
9. General Diagnostic Table..........................................................................41
Page 58 of 2870

AC-2
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
Basic Diagnostics Procedure
1. Basic Diagnostics Procedure
A: PROCEDURE
Step Check Yes No
1 START INSPECTIONS.
1) Perform the pre-inspection.
INSPECTION, General Description.>
2) Perform the self-diagnosis.
OPERATION, Diagnostic Chart for Self-Diag-
nosis.>Does the self-diagnosis oper-
ate?Go to step 2.
C OR SELF-DIAG-
NOSIS SYS-
TEMS DO NOT
OPERATE, Diag-
nostics for A/C
System Malfunc-
tion.>
2 IDENTIFY MALFUNCTION PART.
Identify the malfunction part with self-diagno-
sis.Can the malfunction part be
identified?Repair the mal-
function part in
accordance with
each diagnostic
chart.Go to step 3.
3 CHECK COMPARTMENT TEMPERATURE.
1) Turn ON the A/C switch.
2) Turn the temperature control dial at maxi-
mum cool position.
3) Check the compartment temperature
change.Does the compartment tem-
perature change?Go to step 4.
COMPARTMENT
TEMPERATURE
DOES NOT
CHANGE, OR A/C
SYSTEM DOES
NOT RESPOND
PROMPTLY.,
Diagnostics for A/
C System Mal-
function.>
4 CHECK A/C SYSTEM RESPONSE.
Change the temperature setting, and check the
response of A/C system.Does the A/C system respond
quickly?A/C system is nor-
mal.
COMPARTMENT
TEMPERATURE
DOES NOT
CHANGE, OR A/C
SYSTEM DOES
NOT RESPOND
PROMPTLY.,
Diagnostics for A/
C System Mal-
function.>
Page 59 of 2870

AC-3
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
General Description
2. General Description
A: CAUTION
1) Never connect the battery in reverse polarity.
Auto A/C control module may be destroyed instant-
ly.
2) Do not disconnect the battery terminals while the
engine is running.
A large counter electromotive force will be generat-
ed in the generator, and this voltage may damage
electronic parts such as auto A/C control module,
etc.
3) Before disconnecting the connectors of each
sensor and the auto A/C control module, be sure to
turn off the ignition switch.
Auto A/C control module may be damaged.
4) Every A/C-related part is a precision part. Do not
drop them.
5) Airbag system wiring harness is routed near the
A/C control panel (auto A/C control module) and
junction box.
CAUTION:
For airbag system, yellow-colored wiring har-
ness and connectors are all used. Do not use
the electrical test equipment on these circuits.
Be careful not to damage the airbag system
wiring harness when servicing the A/C control
panel (auto A/C control module) and junction
box.
B: INSPECTION
Before performing the diagnosis, check the follow-
ing items which might affect A/C system problems.
1. BATTERY
1) Measure battery voltage and specific gravity of
electrolyte.
Standard voltage: 12 V
Specific gravity: More than 1.260
2) Check the condition of the fuses for A/C system
power supply and other fuses.
3) Check the condition of harness and harness
connector connections.
2. ASPIRATOR HOSE
1) Turn the ignition switch to ON, and press the A/
C switch.
2) Turn the temperature control dial at maximum
hot position.
3) Press the defroster switch.
4) Turn the fan speed control dial to 4th position.5) Approach a strip of paper (b) in front of the in-ve-
hicle sensor suction port (a) located in the instru-
ment lower cover, and check that air is being
sucked into the port by seeing the paper moving to-
wards port.
NOTE:
Be careful not to let the paper get sucked into port.
6) If the paper does not move at all, remove the in-
strument panel lower cover
MOVAL, Instrument Panel Assembly.> and check
for improper connection of the aspirator hose (a),
in-vehicle sensor and heater unit, and repair them if
necessary.
3. A/C LINE
Check the connection for A/C line (A) and lower
side high-pressure pipe.
4. CONTROL LINKAGE
1) Check the state of mode door linkage.
2) Check the state of air mix door linkage.
3) Check the state of intake door linkage.
AC-00094
(a)
(a)
(b)
AC-00065
(a)
AC-00096
(A)
Page 60 of 2870

AC-4
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
General Description
5. CONTROL SWITCHES
Start and warm-up the engine completely.
1) Inspection using switches
2) Compressor operation inspection
3) Inspection of illumination control
No. Point to check Switch operation Judgment standard
1 Fan speed control dial Turn the fan speed control dial clockwise.Fan speed changes 1st → 2nd → 3rd → 4th
as dial turn.
2AUTO switch1) Press the AUTO switch.
2) Turn the temperature control dial to the left
fully, and set maximum cool position. Outlet air temperature: COOL
Fan speed: 4th
Outlet opening: VENT
Inlet opening: RECIRC
Compressor: AUTO
3) Turn the temperature control dial to the right
slowly, and change the setting from maximum
cool position to maximum hot position gradually. Outlet air temperature: COOL → HOT
Fan speed: AUTO
Outlet opening: AUTO
Inlet opening: AUTO
Compressor: AUTO
4) Turn the temperature control dial to the right
fully, and set maximum hot position. Outlet air temperature: HOT
Fan speed: 4th
Outlet opening: HEAT
Inlet opening: FRESH
Compressor: AUTO
3 Defroster switch Press the defroster switch. Outlet air temperature: AUTO
Fan speed: AUTO
Outlet opening: DEF
Inlet opening: FRESH
Compressor: ON
4FRESH/RECIRC
switchPress the FRESH/RECIRC switch.Inlet opening switches RECIRC → FRESH or
FRESH → RECIRC each time pressing the
switch.
5 Mode control dial Press the mode control dial.Outlet opening switches VENT → BI-LEVEL
→ HEAT → DEF/HEAT each time dialing
clockwise.
No. Point to check Switch operation Judgment standard
1 Compressor1) A/C switch is turned to ON.
2) Turn the fan speed control clockwise.Compressor: ON
No. Point to check Switch operation Judgment standard
1 Illumination1) Turn the lighting switch to ON. Illumination comes on.
2) Press the OFF switch one second or more. Illumination dimming is cancelled.
Page 61 of 2870
AC-5
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
Electrical Component Location
3. Electrical Component Location
A: LOCATION
1. ENGINE COMPARTMENT
(1) A/C compressor (3) Pressure switch (4) Ambient sensor
(2) A/C relay
AC-00097 (1)
(2)
(4)
(1)
(3)
(2)
(3)
Page 62 of 2870
AC-6
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
Electrical Component Location
2. PASSENGER COMPARTMENT
(1) Mode door actuator (4) Intake door actuator (7) Air mix door actuator
(2) In-vehicle sensor (5) Blower motor
(3) Sunload sensor (6) Evaporator sensor
AC-00098
(1) (6)(4)
(5) (7)(7)(6)(5) (4) (3)
(1) (2)
(3)
Page 63 of 2870

AC-7
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
Auto A/C Control Module I/O Signal
4. Auto A/C Control Module I/O Signal
A: ELECTRICAL SPECIFICATION
Terminal No. Content Measuring conditionSpecified
value
B9
Mode door actuator power supplyChanges outlet from VENT to DEF.
*2
B8 Changes outlet from DEF to VENT.
B7
Air mix door actuator power supplyChanges air mix door from COOL to HOT.
*1
B6 Changes air mix door from HOT to COOL.
B5 IGN power supply Ignition switch: ON Battery voltage
B4 Battery power supply Ignition switch: OFF, ACC, ON Battery voltage
B3 Sunload sensorIgnition switch: ON and under normal sunload
(without sunload: 5 V)3 V
B2 Evaporator sensor Ignition switch: ON 5 V or less
B1 Air mix door actuator P.B.R. signalAir mix door: COOL position 0.5 V
Air mix door: HOT position 4.5 V
B20
Intake door actuator signalAir inlet: FRESH (other positions: 12 V) 0 V
B19 Air inlet: MIX (other positions: 12 V) 0 V
B18 Air inlet: RECIRC (other positions: 12 V) 0 V
B17 A/C ON signal A/C: ON (A/C OFF: 0 V) 8 — 10 V
B16 Blower motor control *3 *3
B15 Blower fan ON signalWhen blower fan running (when blower fan not
running: 12 V)0 V
B13 Engine coolant temperature sensor When the engine coolant is at 49°C (120°F) 8.9 V
B12 In-vehicle sensor — —
B11 Ground When there is continuity to chassis ground 0 Ω
A7 Air mix door actuator P.B.R. reference voltage Ignition switch: ON 5 V
A5 Mode door actuator position detection signal OutletBI-LEVEL, DEF 5 V
VENT, HEAT, DEF/HEAT 0 V
A4 Mode door actuator position detection signal OutletHEAT, DEF/HEAT, DEF 5 V
VENT, BI-LEVEL 0 V
A1 Illumination power supplyIgnition switch: ON, light switch: ON Battery voltage
Ignition switch: ON, light switch: OFF 0 V
A16 Sensor ground When there is continuity to chassis ground 0 Ω
AC-00099
1 2 3 4 5 6 7 8 910
11 12 13 14 15 16 17 18 19 201 2 3 4 5 6 7 8
9
10 11 12 13 14 15 16
i48B: To A:To
i49
Page 64 of 2870
AC-8
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
Auto A/C Control Module I/O Signal
*1: Battery voltage is indicated when motor running, 0 V or battery voltage pulse signal is output when motor stops.
*2: Battery voltage is indicated when motor running, 0 V is indicated when motor stops.
*3: Voltage can not be measured because of pulse signal.
B: WIRING DIAGRAM:
A14Combination meter (ambient temperature sig-
nal)*3 *3
A13 Mode door actuator position detection signal OutletVENT, BI-LEVEL, HEAT 5 V
DEF/HEAT, DEF 0 V
A12 Mode door actuator position detection signal OutletVENT, DEF/HEAT 5 V
BI-LEVEL, HEAT, DEF 0 V
A10 A/C cutout signalA/C: ON Battery voltage
Pressure switch operated 0 V
A9 Illumination ground When there is continuity to chassis ground 0 Ω Terminal No. Content Measuring conditionSpecified
value