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Contents Section: Automatic HVAC System All sections

HVAC System (auto A/c) (diagnostics) Subaru Impreza WRX GH

Automatic HVAC System 18 illustrations ~1085 words

PROCEDURE

StepCheckYesNo
1 START INSPECTIONS. Perform the pre-inspection. INSPECTION, General Description. > Perform the self-diagnosis. OPERATION, Diagnostic Chart for Self-diagnosis. >Does the self-diagnosis operate?Go to step 2 .A/C OR SELF DIAGNOSIS FUNCTION FAILS TO OPERATE, Diagnostics for A/C System Malfunction. >
2 IDENTIFY MALFUNCTION PART. Identify the malfunction part with self-diagnosis.Can the malfunction part be confirmed?Repair the malfunctioning part in accordance with each diagnostic chart.Go to step 3 .
3 CHECK COMPARTMENT TEMPERATURE. Turn the A/C switch to ON. Turn the temperature control dial at maximum cool position. Check the compartment temperature change.Does the compartment temperature change?Go to step 4 .COMPARTMENT TEMPERATURE DOES NOT CHANGE, OR A/C SYSTEM DOES NOT RESPOND PROMPTLY, Diagnostics for A/C System Malfunction. >
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 normal.COMPARTMENT TEMPERATURE DOES NOT CHANGE, OR A/C SYSTEM DOES NOT RESPOND PROMPTLY, Diagnostics for A/C System Malfunction. >

DIAGNOSIS PROCEDURE

CAUTION

  1. Never connect the battery in reverse polarity. Doing so may immediately damage the auto A/C control module.
  2. Do not disconnect the battery terminals while the engine is running. A large counter electromotive force will be generated in the generator, and this voltage may damage electronic parts such as auto A/C control module etc.
  3. Before disconnecting the connectors of sensors 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 and junction box.
CAUTIONDo not use electrical test equipment on the airbag system wiring harness and connector. Be careful not to damage the airbag system wiring harness when servicing the A/C control panel and junction box.

INSPECTION

Before performing the diagnosis, check the following items which may cause problems in the A/C system.

BATTERY

  1. Measure the battery voltage and specific gravity of the electrolyte. Standard voltage: 12 V Specific gravity: 1.260 or more
  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.

Scheme 125

Scheme 125: ASPIRATOR HOSE
Scheme 125: ASPIRATOR HOSE
  1. Turn the ignition switch to ON, and press the A/C switch.
  2. Turn the temperature control dial to maximum hot position.
  3. Set the air flow control dial to the "DEF" position.
  4. Turn the fan switch to MAX.
  5. Put a thin strip of paper close to the front side of in-vehicle sensor suction port (A) at the instrument panel lower cover, and check whether the strip becomes drawn towards the port, indicating that air is being drawn in at the port. NOTE: Be careful not to let the paper get sucked into the port.
  6. If the paper strip does not move at all, remove the center console INSTRUMENT PANEL, LOWER , REMOVAL, Center Console . >, and check for improper connection of the aspirator hose (A), in-vehicle sensor and heater unit, and repair them if necessary.

Scheme 126

Scheme 126
Scheme 126

A/C LINE

Check the connection for A/C line (A) and lower side high-pressure pipe.

Scheme 127

Scheme 127: A/C LINE
Scheme 127: A/C LINE

CONTROL LINKAGE

  1. Check the state of mode door linkage.
  2. Check the state of air mix door linkage.
  3. Check the state of FRESH/RECIRC door linkage.

CONTROL SWITCHES

Start the engine and warm-up completely.

  1. Inspection using switches SWITCH OPERATION CHART No. Point to check Switch operation Judgment standard 1 Air flow control dial Turn the dial to the right. Outlet opening (mode) switches AUTO --> VENT --> BI-LEVEL --> HEAT --> DEF/HEAT --> DEF each time turning the dial. 2 Fan speed control dial Turn the dial to the right. Fan speed switches OFF --> AUTO --> 1st --> 2nd --> 3rd --> 4th --> 5th --> 6th --> 7th each time the dial is turned. 3 FRESH/RECIRC switch Press the FRESH/RECIRC switch. Inlet opening switches RECIRC --> FRESH --> RECIRC each time pressing the switch. (LED illuminates at RECIRC) Keep the FRESH/RECIRC switch pressed for a while. (0.7 seconds or more) The LED blinks twice and the system switches to AUTO. 4 A/C switch Turn the A/C switch to ON with the fan speed control dial set to except for OFF position. The LED lights and the compressor operates. Keep the FRESH/RECIRC switch pressed for a while. (0.7 seconds or more) The LED blinks twice and the system switches to AUTO. 5 Auto function Operate in order starting from 1). Set the following dial and switch to AUTO. Air flow control dial Fan speed control dial FRESH/RECIRC switch A/C switch Turn the temperature control dial completely to the left, and set to the maximum cool position. Outlet air temperature: COOL Fan speed: Max. Outlet opening: VENT Inlet opening: RECIRC Compressor: AUTO 3) Turn the temperature control dial to the right slowly up to the maximum hot position. Outlet air temperature: COOL --> HOT Fan speed: AUTO Outlet opening: AUTO Inlet opening: AUTO Compressor: AUTO 4) Turn the temperature control dial fully to the right, to the maximum hot position. Outlet air temperature: HOT Fan speed: Max. Outlet opening: HEAT Inlet opening: FRESH Compressor: AUTO 6 Defroster Interlock Function Set the air flow control dial to the DEF or the DEF/HEAT position. Outlet air temperature: AUTO Fan speed: AUTO Outlet opening: DEF or DEF/HEAT Inlet opening: FRESH Compressor: ON 7 Rear defogger switch Press the rear defogger switch. LED illuminates.
  2. Compressor operation inspection SWITCH OPERATION CHART No. Point to check Switch operation Judgment standard 1 Compressor Turn the A/C switch to ON. Set the FAN switch between LO and HI. Compressor: ON
  3. Inspection of illumination control
No.Point to checkSwitch operationJudgment standard
1IlluminationTurn the lighting switch to ON.Illumination becomes lit. If the LED is lit, the LED will dim.

SWITCH OPERATION CHART

Scheme 128

Scheme 128: ENGINE COMPARTMENT
Scheme 128: ENGINE COMPARTMENT

Scheme 129

Scheme 129
Scheme 129

Scheme 130

Scheme 130: COMPARTMENT
Scheme 130: COMPARTMENT

Scheme 131

Scheme 131: ELECTRICAL SPECIFICATION
Scheme 131: ELECTRICAL SPECIFICATION
Terminal No.ContentsMeasuring conditionStandard
1Mode actuator #4Actuator active8 V or more
2Mode actuator #3Actuator active8 V or more
3Mode actuator #2Actuator active8 V or more
4Mode actuator #1Actuator active8 V or more
6Intake door actuator (FRESH air)Fresh air condition1 V or less
7Intake door actuator (MIX)MIX condition1 V or less
8Intake door actuator (RECIRCULATED air)Recirculated air condition1 V or less
9Blower fan ON signalWhen blower fan is turned to ON.1 V or less
10Rr defogger operation signal inputWhen Rr defogger is active10 V or more
11A/C cut signalWhen A/C is cut1 V or less
14Sensor GNDAlways1 V or less
15ACC power supplyACC ONBattery voltage
16Sunload sensorWhen exposed to sunlight4.5 V
17RECIRC sensorIgnition switch ON25°C: 1 - 5 V
18After evaporator sensorChanges according to the temperature after passing through the evaporator1 - 4.5 V
19CAN LoUnable to measure the voltage because of digital signal.
20CAN HiUnable to measure the voltage because of digital signal.
25Air mix actuator #4Air mix actuator active8 V or more
26Air mix actuator #3Air mix actuator active8 V or more
27Air mix actuator #2Air mix actuator active8 V or more
28Air mix actuator #1Air mix actuator active8 V or more
31BATTAlwaysBattery voltage
32IGNIgnition ONBattery voltage
34GNDAlways1 V or less
36A/C ON signalWhen A/C is active8 V or more
35ILLIllumination ON (measure between 37 - 35)Battery voltage
37ILL+
39Rr defogger switch outputWhen rear defogger relay is ONBattery voltage
40Fan control signalIgnition switch ON, Blower switch ON8 V or more

TERMINAL SPECIFICATIONS

AIR CONDITIONER AUTO A/C MODEL

AIR CONDITIONING . >

Scheme 132

Scheme 132: OPERATION
Scheme 132: OPERATION

A/C CONTROL PANEL SELF-DIAGNOSIS

StepCheckYesNo
1 SELECT SELF-DIAGNOSIS MODE IN THE CONTROL PANEL. Set the air flow control dial and fan speed control dial to the AUTO position. Start the engine with the A/C switch pressed.Does the self-diagnosis mode operate?Go to step 2 .A/C OR SELF DIAGNOSIS FUNCTION FAILS TO OPERATE, Diagnostics for A/C System Malfunction. >
2 CHECK THE LIGHTING OF THE LED. Make sure that all switch LEDs on the control panel illuminate.Do all LEDs blink eight times?Go to step 3 .Replace the control panel.
3 CHECK SENSOR MALFUNCTION. Set the air flow control dial and fan speed control dial to the AUTO position. If the system has trouble for each sensor, the FRESH/RECIRC switch LED is turned off. (Blinks during diagnosis) If the system has no trouble, the FRESH/RECIRC switch LED illuminates.Does the FRESH/RECIRC switch LED illuminate?Go to step 5 .Go to step 4 .
4 CONFIRM MALFUNCTIONING SENSOR. Set the air flow control dial to the AUTO position. Turn the fan speed control dial to each mode position, and check each switch LED illumination according to the sensor check table. SENSOR CHECK TABLE, OPERATION, Diagnostic Chart for Self-diagnosis. >When the fan speed control dial is set to the individual mode positions, does the FRESH/RECIRC switch LED turn off?Go to step 5 .Repair the defective sensor. DIAGNOSTIC PROCEDURE FOR SENSORS. >
5 CHECK AIR MIX DOOR AND MODE DOOR POSITION SIGNALS. Set the air flow control dial to the FACE position. Turn the fan speed control dial to AUTO. If the system has trouble for air mix door signal and mode door position signal, the FRESH/RECIRC switch LED is turned off or blinks. If the system has no trouble, the FRESH/RECIRC switch LED illuminates.Does the FRESH/RECIRC switch LED illuminate?Go to step 6 .Check the mode door actuator circuit. MODE DOOR ACTUATOR, Diagnostic Procedure for Actuators. >
6 CHECK AIR MIX DOOR AND MODE DOOR POSITION DRIVE SIGNALS. Set the air flow control dial to the FACE position. Set the fan speed control dial to each position, and check the lighting conditions of each LED. A/C CONTROL PANEL SELF-DIAGNOSIS, OPERATION, Diagnostic Chart for Self-diagnosis. >Does the lighting conditions of the LED match the drive signal list?Go to step 7 .Check the air mix door actuator circuit. AIR MIX DOOR ACTUATOR, Diagnostic Procedure for Actuators. >
7 CHECK AIR MIX DOOR AND MODE DOOR POSITION DRIVE SIGNALS. Press the A/C switch. Set the fan speed control dial to each position, and check the lighting conditions of each LED. A/C CONTROL PANEL SELF-DIAGNOSIS, OPERATION, Diagnostic Chart for Self-diagnosis. >Does the lighting conditions of the LED match the drive signal list?Go to step 8 .Check the mode door actuator circuit. MODE DOOR ACTUATOR, Diagnostic Procedure for Actuators. >
8 CHECK OPERATION OF EACH ACTUATOR, BLOWER FAN AND COMPRESSOR CLUTCH. Set the air flow control dial to the B/L position. Set the fan speed control dial to AUTO - 7th position, and select the operating mode. Check the operation of each mode according to operating mode table. A/C CONTROL PANEL SELF-DIAGNOSIS, OPERATION, Diagnostic Chart for Self-diagnosis. > FRESH/RECIRC door Air flow control door Air mix door Blower fan A/C compressorDoes the operation of each mode match to operating mode table?Turn the fan speed control dial to OFF or turn the ignition switch to OFF, to complete the self diagnosis.Repair the malfunctioning part in accordance with each diagnostic chart.

DIAGNOSIS PROCEDURE

SENSOR CHECK TABLE

Note. When the sunload sensor check is performed indoors or in the shade, it could be diagnosed as having an open circuit. Always check the sunload sensor at a location exposed to direct sunlight.

Air flow control dial positionFan dial positionSensorNo troubleShort circuitOpen circuitWhen currently malfunctioningWhen having malfunctioned in the past
AUTOAUTOIn-vehicle sensorFRESH/RECIRC switch LED is turned offFRESH/RECIRC switch LED blinks (Illuminates for 0.2 sec. <=> turns off for 0.2 sec.)FRESH/RECIRC switch LED blinks (Illuminates for 1 sec. <=> turns off for 1 sec.)Rear window defogger switch LED is turned offRear window defogger switch LED illuminates
1stAmbient sensorFRESH/RECIRC switch LED blinks (Illuminates for 0.2 sec. <=> turns off for 0.2 sec.)
2ndEvaporator sensorFRESH/RECIRC switch LED blinks (Illuminates for 0.2 sec. <=> turns off for 0.2 sec.)
3rdEngine coolant temperature sensor
4thSunload sensorFRESH/RECIRC switch LED blinks (Illuminates for 0.2 sec. <=> turns off for 0.2 sec.)
5th - 7thCAN communication

SENSOR CHECK CHART

OPERATING MODE TABLE

OperationFan speed control dial position
AUTO1st2nd3rd4th5th6th7th
Blower fan4V4V4.9 V5.9 V7.0 V8.3 V9.8 V14 V
FRESH/RECIRC doorRECIRCRECIRCMIXFRESHFRESHFRESHFRESHFRESH
Air flow control doorFACEFACEFACEB/LHEATHEATD/HD/H
Air mix door0%0%0%50%50%100%100%100%
A/C compressorOFFONONONONONONON

OPERATING MODE CHART

DRIVE PROGRESS CHECK TABLE

Air flow control dial positionFan speed control dial positionDrive signal to checkA/C switch LEDNo troubleShort circuitOpen circuitWhen currently malfunctioningWhen having malfunctioned in the past
FACEAUTOMIX #1Blinking (Illuminates for 0.2 sec. <=> turns off for 0.2 sec.)FRESH/RECIRC switch LED is turned offFRESH/RECIRC switch LED blinks (Illuminates for 0.2 sec. <=> turns off for 0.2 sec.)FRESH/RECIRC switch LED blinks (Illuminates for 1 sec. <=> turns off for 1 sec.)Rear window defogger switch LED is turned offRear window defogger switch LED illuminates
1stMIX #2
2ndMIX #3
3rd - 7thMIX #4
AUTOMODE #1Blinking (Illuminates for 1 sec. <=> turns off for 1 sec.)
1stMODE #2
2ndMODE #3
3rd - 7thMODE #4

DRIVE PROGRESS CHECK CHART

TROUBLE SYMPTOM

  1. Set temperature is not indicated on the display, switch LEDs are faulty and switches do not operate.
  2. Self-diagnosis system does not operate.

Scheme 133

Scheme 133: WIRING DIAGRAM
Scheme 133: WIRING DIAGRAM
StepCheckYesNo
1 CHECK FUSE. Turn the ignition switch to OFF. Remove the fuse No. 7 from main fuse box. Check the condition of fuse.Is the fuse blown out?Replace the fuse.Go to step 2 .
2 CHECK FUSE. Turn the ignition switch to OFF. Remove the fuse No. 22 and No. 31 from fuse & relay box. Check the condition of fuse.Is the fuse blown out?Replace the fuse.Go to step 3 .
3 CHECK A/C CONTROL MODULE POWER CIRCUIT. Remove the A/C control panel. Disconnect the A/C control panel harness connector. Measure the voltage between A/C control panel harness connector terminal and chassis ground after turning the ignition switch to ACC. Connector & terminal (i88) No. 15 (+) - Chassis ground (-)Is the voltage 10 V or more?Go to step 4 .Check for open or short circuit in the harness between A/C control panel and fuse.
4 CHECK A/C CONTROL MODULE POWER CIRCUIT. Measure the voltage between A/C control panel harness connector terminal and chassis ground after turning the ignition switch to ON. Connector & terminal (i88) No. 32 (+) - Chassis ground (-)Is the voltage 10 V or more?Go to step 5 .Check for open or short circuit in the harness between A/C control panel and fuse.
5 CHECK A/C CONTROL PANEL GROUND POWER CIRCUIT. Measure the resistance of harness between A/C control panel and chassis ground after turning the ignition switch to OFF. Connector & terminal (i88) No. 34 - Chassis groundIs resistance less than 10 ohms?Go to step 6 .Repair the harness for ground line.
6 CHECK POOR CONTACT. Check poor contact of auto A/C control module connector.Is there poor contact in connector?Repair the connector.Replace the auto A/C control module.

DIAGNOSIS PROCEDURE

  1. Blower motor does not rotate.
  2. Blower motor does not change speeds.

Scheme 134

Scheme 134: WIRING DIAGRAM
Scheme 134: WIRING DIAGRAM
StepCheckYesNo
1 CHECK FUSE. Remove fuse No. 22,27 and 28 from the fuse & relay box. Check the condition of fuse.Is any fuse blown out?Replace the fuse.Go to step 2 .
2 CHECK BLOWER MOTOR RELAY POWER SUPPLY. Turn the ignition switch to OFF. Remove the blower motor relay. Turn the ignition switch to ON. Use a tester to measure the voltage between the blower motor relay connector and chassis ground. Connector & terminal (B87) No. 2 - Chassis groundIs the voltage 10 V or more?Go to step 3 .Repair the open circuit of blower motor power supply line harness.
3 CHECK BLOWER MOTOR RELAY POWER SUPPLY. Turn the ignition switch to ON. Turn the blower switch to ON. Use a tester to measure the voltage between the blower motor relay connectors. Connector & terminal (B386) No. 2 - No. 4Is the voltage 10 V or more?Go to step 5 .Go to step 4 .
4 CHECK HARNESS. Turn the ignition switch to OFF. Disconnect the auto A/C control module connector (i88). Use a tester to measure the resistance between harness terminals. Connector & terminal (B386) No. 4 - (i88) No. 9Is the resistance less than 10 ohms?Go to step 5 .Repair or replace the open circuit of the harness.
5 CHECK BLOWER MOTOR RELAY. Turn the ignition switch to OFF. Remove the blower motor relay. Connect the battery terminal to the blower motor relay. No. 2 - No. 4: Measure the resistance between terminals. Terminals No. 1 - No. 5Is resistance less than 1 ohms?Go to step 6 .Replace the blower motor relay.
6 CHECK BLOWER MOTOR POWER SUPPLY. Turn the ignition switch to OFF. Install the blower motor relay. Disconnect the blower motor connector. Turn the ignition switch to ON. Turn the blower switch to ON. Use a tester to measure the voltage between the blower motor connector and chassis ground. Connector & terminal (B87) No. 2 - Chassis groundIs the voltage 10 V or more?Go to step 7 .Repair or replace the harness between the blower motor relay and the blower motor.
7 CHECK BLOWER MOTOR. Disconnect the connector from the blower motor. Connect the battery positive terminal to terminal No. 2 of blower motor connector, and negative terminal to terminal No. 1. Make sure the blower motor runs.Does the blower motor run?Go to step 8 .Replace the blower motor.
8 CHECK HARNESS. Turn the ignition switch to OFF. Disconnect the power transistor connector. Disconnect the auto A/C control module connector. Use a tester to measure the resistance between harness terminals. Connector & terminal (B57) No. 1 - Chassis ground: (B57) No. 2 - (i88) No. 40: (B57) No. 3 - (B87) No. 1: (B57) No. 4 - (B87) No. 2: (B57) No. 4 - (B386) No. 5Is the resistance less than 10 ohms?Go to step 9 .Repair or replace the harness.
9 CHECK FAN CONTROL SIGNAL. Turn the ignition switch to OFF. Connect the blower motor and auto A/C control module. Turn the ignition switch to ON. Set the fan dial to 1st - 7th. Use a tester to measure the voltage between the power transistor connector and chassis ground.Is approx. 10 V detected in 1st, and 1 V at 7th?Replace the power transistor. REMOVAL , Power Transistor (Auto A/C Model) . >Go to step 10 .
10 CHECK POOR CONTACT. Check poor contact of auto A/C control module connector.Is there poor contact in connector?Repair the connector.Replace the auto A/C control module.

DIAGNOSIS PROCEDURE

  1. The blower turns even though the blower switch is not turned ON.
  2. The blower motor continues to turn at high speed. (Cannot be adjusted.)

WIRING DIAGRAM

StepCheckYesNo
1 CHECK BLOWER MOTOR CIRCUIT. Turn the ignition switch to OFF. Disconnect the power transistor connector. Use a tester to measure the resistance between the connector and chassis ground. Connector & terminal (B57) No. 3 - Chassis groundIs the resistance 10 ohms or more?Go to step 2 .Repair or replace the harness.
2 CHECK POWER TRANSISTOR. Measure the resistance between power transistor terminals with a tester. Connector & terminal (B57) No. 3 - No. 1Is resistance less than 10 ohms?Replace the power transistor. REMOVAL , Power Transistor (Auto A/C Model) . >Go to step 3 .
3 CHECK HARNESS. Remove the auto A/C control module. Use a tester to measure the resistance between the power transistor connector and chassis ground. Connector & terminal (B57) No. 2 - Chassis groundIs resistance less than 10 ohms?Repair or replace the short circuit of the harness.Replace the auto A/C control module.

DIAGNOSIS PROCEDURE

  1. Compartment temperature does not change (Cold air does not come out).
  2. The A/C system does not respond (Response is extremely slow).

Scheme 135

Scheme 135: WIRING DIAGRAM
Scheme 135: WIRING DIAGRAM
StepCheckYesNo
1 CHECK FUSE. Turn the ignition switch to OFF. Remove the fuse No. 22 from fuse & relay box. Check the condition of fuse.Is the fuse blown out?Replace the fuse.Go to step 2 .
2 CHECK SIGNAL TO A/C RELAY AND AUTO A/C CONTROL MODULE. Disconnect the A/C relay and auto A/C control module harness connector. Turn the ignition switch to ON. Measure the voltage between A/C relay connector terminal and chassis ground. Measure the voltage between auto A/C control module harness connector terminal and chassis ground. Connector & terminal (F27) No. 17 (+) - Chassis ground (-): (i88) No. 11 (+) - Chassis ground (-)Is the voltage 10 V or more?Go to step 5 .Go to step 3 .
3 CHECK POWER SUPPLY FOR PRESSURE SWITCH. Turn the ignition switch to OFF. Disconnect the pressure switch harness connector. Turn the ignition switch to ON. Measure the voltage between pressure switch harness connector terminal and chassis ground. Connector & terminal (B10) No. 2 (+) - Chassis ground (-)Is the voltage 10 V or more?Go to step 4 .Check for open or short circuit in the harness between fuse and pressure switch.
4 CHECK HARNESS BETWEEN PRESSURE SWITCH AND A/C RELAY, AUTO A/C CONTROL MODULE. Turn the ignition switch to OFF. Measure the resistance of harness between pressure switch connector and A/C relay connector. Measure the resistance of harness between pressure switch connector and auto A/C control module connector. Connector & terminal (B10) No. 2 - (F27) No. 17: (B10) No. 2 - (i88) No. 11Is resistance less than 1 ohms?Check the pressure switch. INSPECTION , Pressure Switch (Triple Pressure Switch) . >Repair the harness.
5 CHECK POWER SUPPLY FOR A/C RELAY. Measure the voltage between A/C relay connector terminal and chassis ground. Connector & terminal (F27) No. 14 (+) - Chassis ground (-)Is the voltage 10 V or more?Go to step 6 .Check open or short circuit of harness between fuse and A/C relay.
6 CHECK A/C RELAY. Check the A/C relay. INSPECTION , Relay and Fuse . >Is there a malfunction in the A/C relay?Go to step 7 .Replace the A/C relay.
7 CHECK A/C ON SIGNAL. Turn the ignition switch to OFF. Connect the A/C relay and all disconnected connectors. Start the engine and turn the A/C switch to ON. Turn the temperature control dial at maximum cool position. Measure the voltage between auto A/C control module harness connector terminal and chassis ground. Connector & terminal (i88) No. 36 (+) - Chassis ground (-)Is the voltage 5.5 V or more?Go to step 9 .Go to step 8 .
8 CHECK HARNESS BETWEEN AUTO A/C CONTROL MODULE AND ECM. Turn the ignition switch to OFF. Disconnect the harness connector of auto A/C control module and ECM. Measure the resistance of harness between auto A/C control module connector and ECM connector. Connector & terminal (i88) No. 36 - (B136) No. 24Is resistance less than 1 ohms?Replace the auto A/C control module.Repair the harness.
9 CHECK MAGNET CLUTCH ON SIGNAL. Stop the engine and turn the A/C switch to OFF. Turn the ignition switch to ON. Measure the voltage between ECM connector terminal and chassis ground. Connector & terminal (B136) No. 9 (+) - Chassis ground (-)Is the voltage 10 V or more?Go to step 10 .Check for open or short circuit in the harness between A/C relay and ECM.
10 CHECK MAGNET CLUTCH ON SIGNAL. Start the engine and turn the A/C switch to ON. Turn the temperature control dial at maximum cool position. Measure the voltage between ECM connector terminal and chassis ground. Connector & terminal (B136) No. 9 (+) - Chassis ground (-)Is the voltage 0 V?Go to step 11 .Replace the ECM.
11 CHECK POWER SUPPLY FOR MAGNET CLUTCH. Stop the engine and turn the A/C switch to OFF. Disconnect the harness connector of magnet clutch. Start the engine and turn the A/C switch to ON. Turn the temperature control dial at maximum cool position. Measure the voltage between magnet clutch harness connector terminal and chassis ground. Connector & terminal (F24) No. 1 (+) - Chassis ground (-)Is the voltage 10 V or more?Inspect the compressor. INSPECTION , Compressor . >Check for open or short circuit in the harness between A/C relay and magnet clutch.

DIAGNOSIS PROCEDURE

FRESH/RECIRC mode is not changed.

Scheme 136

Scheme 136: WIRING DIAGRAM
Scheme 136: WIRING DIAGRAM
StepCheckYesNo
1 CHECK POWER SUPPLY FOR INTAKE DOOR ACTUATOR. Turn the ignition switch to OFF. Disconnect the intake door actuator connector. Turn the ignition switch to ON. Measure the voltage between intake door actuator connector and chassis ground. Connector & terminal (B163) No. 1 (+) - Chassis ground (-)Is the voltage 7 V (at normal temperature) ?Go to step 2 .Check for open or short circuit in the harness between intake door actuator and fuse.
2 CHECK HARNESS BETWEEN AUTO A/C CONTROL MODULE AND INTAKE DOOR ACTUATOR. Turn the ignition switch to OFF. Disconnect the auto A/C control module connector. Measure the resistance between intake door actuator connector and auto A/C control module connector. Connector & terminal (i88) No. 8 - (B163) No. 6: (i88) No. 7 - (B163) No. 5: (188) No. 6 - (B163) No. 4Is resistance less than 1 ohms?Go to step 3 .Repair the harness between auto A/C control module and intake door actuator.
3 CHECK OPERATION OF INTAKE DOOR ACTUATOR. Connect the intake door actuator connector. Ground the auto A/C control module connector with a suitable wire. Turn the ignition switch to ON, and check the operation of intake door actuator. Connector & terminal (B163) No. 4 - Chassis groundDoes the actuator move to the FRESH side?Go to step 4 .Replace the intake door actuator.
4 CHECK OPERATION OF INTAKE DOOR ACTUATOR. Turn the ignition switch to OFF. Ground the auto A/C control module connector with a suitable wire. Turn the ignition switch to ON, and check the operation of intake door actuator. Connector & terminal: (B163) No. 5 - Chassis groundDoes the actuator move to the RECIRC side?Replace the auto A/C control module.Replace the intake door actuator.

DIAGNOSIS PROCEDURE

Air flow outlet is not changed.

Scheme 137

Scheme 137: WIRING DIAGRAM
Scheme 137: WIRING DIAGRAM
StepCheckYesNo
1 CHECK POWER SUPPLY FOR MODE DOOR ACTUATOR. Turn the ignition switch to OFF. Disconnect the mode door actuator connector. Turn the ignition switch to ON. Measure the voltage between the mode door actuator connector terminal and chassis ground. Connector & terminal (B77) No. 3 (+) - Chassis ground (-)Is the voltage approx. 10 V or more?Go to step 2 .Repair the DC power supply circuit.
2 CHECK MODE DOOR ACTUATOR. Disconnect the mode door actuator connector. Use a tester to measure the resistance between mode door actuator terminals. Connector & terminal (B77) No. 3 - No. 1: (B77) No. 3 - No. 2: (B77) No. 3 - No. 5: (B77) No. 3 - No. 6Is the resistance between 80 - 100 ohms?Go to step 3 .Replace the mode door actuator.
3 CHECK HARNESS BETWEEN AUTO A/C CONTROL MODULE AND MODE DOOR ACTUATOR. Turn the A/C and ignition switch to OFF. Disconnect the auto A/C control module connector. Measure the resistance between auto A/C control module and mode door actuator connector. Connector & terminal (B77) No. 1 - (i88) No. 4: (B77) No. 2 - (i88) No. 3: (B77) No. 5 - (i88) No. 2: (B77) No. 6 - (i88) No. 1Is the resistance less than 1 ohms?Go to step 4 .Repair the harness between auto A/C control module and mode door actuator.
4 CHECK POOR CONTACT. Check poor contact of auto A/C control module and connector.Is there poor contact in connector?Repair the connector.Replace the auto A/C control module.

DIAGNOSIS PROCEDURE

Outlet air temperature does not change.

Scheme 138

Scheme 138: WIRING DIAGRAM
Scheme 138: WIRING DIAGRAM
StepCheckYesNo
1 CHECK AIR MIX DOOR ACTUATOR POWER SUPPLY. Turn the ignition switch to OFF. Disconnect the air mix door actuator connector. Turn the ignition switch to ON. Measure the voltage between the air mix door actuator connector terminal and chassis ground. Connector & terminal (B239) No. 3 (+) - Chassis ground (-)Is the voltage approx. 10 V or more?Go to step 2 .Repair the DC power supply circuit.
2 CHECK AIR MIX DOOR ACTUATOR. Disconnect the air mix door actuator connector. Connect the negative terminal of the battery to the next terminal. Use a tester to measure the resistance between the air mix actuator terminals. Connector & terminal (B239) No. 3 - No. 1: (B239) No. 3 - No. 2: (B239) No. 3 - No. 5: (B239) No. 3 - No. 6Is the resistance between 80 - 100 ohms?Go to step 3 .Replace the air mix door actuator.
3 CHECK HARNESS BETWEEN AUTO A/C CONTROL MODULE AND AIR MIX DOOR ACTUATOR. Turn the A/C and ignition switch to OFF. Disconnect the auto A/C control module connector. Measure the resistance between auto A/C control module and air mix door actuator connector. Connector & terminal (B239) No. 1 - (i88) No. 28: (B239) No. 2 - (i88) No. 27: (B239) No. 5 - (i88) No. 26: (B239) No. 6 - (i88) No. 25Is the resistance less than 1 ohms?Go to step 4 .Repair the harness between auto A/C control module and air mix door actuator.
4 CHECK POOR CONTACT. Check poor contact of auto A/C control module and connector.Is there poor contact in connector?Repair the connector.Replace the auto A/C control module.

DIAGNOSIS PROCEDURE

  1. Fan speed is not switched when the fan speed control dial is in AUTO position.
  2. Failure related to the ambient sensor is indicated in self-diagnosis.

Scheme 139

Scheme 139: WIRING DIAGRAM
Scheme 139: WIRING DIAGRAM
StepCheckYesNo
1 CHECK AMBIENT SENSOR. Turn the ignition switch to OFF. Disconnect the connector from ambient sensor. Measure the resistance between terminals of ambient sensor. Terminals No. 1 - No. 2Is the resistance approximately 3 kohms at 25°C (77°F)?Go to step 2 .Replace the ambient sensor.
2 CHECK INPUT SIGNAL FOR AMBIENT SENSOR. Turn the ignition to ON. Measure the voltage between connector (F78) terminals. Connector & terminal (F78) No. 1 (+) - No. 2 (-)Is the voltage approx. 5 V?Go to step 6 .Go to step 3 .
3 CHECK COMBINATION METER OUTPUT SIGNAL. Turn the ignition switch to OFF. Pull out the combination meter. Disconnect the connector from ambient sensor. Turn the ignition switch to ON. Measure the voltage between the combination meter connector terminals. Connector & terminal (i10) No. 24 (+) - No. 23 (-)Is the voltage approx. 5 V?Go to step 4 .Go to step 6 .
4 CHECK HARNESS CONNECTOR BETWEEN COMBINATION METER AND AMBIENT TEMPERATURE SENSOR. Turn the ignition switch to OFF. Disconnect the connector from combination meter. Measure the resistance of the harness between the combination meter and ambient temperature sensor. Connector & terminal (F78) No. 1 - (i10) No. 24Is the resistance less than 1 ohms?Go to step 5 .Repair the open circuit in the harness between the combination meter and ambient temperature sensor.
5 CHECK HARNESS CONNECTOR BETWEEN COMBINATION METER AND AMBIENT TEMPERATURE SENSOR. Measure the resistance of the harness between the combination meter and ambient temperature sensor. Connector & terminal (F78) No. 2 - (i10) No. 23Is resistance less than 1 ohms?Replace the combination meter.Repair the open circuit in the harness between the combination meter and ambient temperature sensor.
6 CHECK HARNESS CONNECTOR BETWEEN COMBINATION METER AND AUTO A/C CONTROL MODULE. Turn the ignition switch to OFF. Disconnect the connector from the combination meter. Disconnect the auto A/C control module connector. Measure the resistance of the harness between the combination meter and auto A/C control module. Connector & terminal (i88) No. 19 - (i10) No. 26Is resistance less than 1 ohms?Go to step 7 .Repair the open circuit in the harness between the combination meter and auto A/C control module.
7 CHECK HARNESS CONNECTOR BETWEEN COMBINATION METER AND AUTO A/C CONTROL MODULE. Measure the resistance of the harness between the combination meter and auto A/C control module. Connector & terminal (i88) No. 20 - (i10) No. 27Is resistance less than 1 ohms?Go to step 8 .Repair the open circuit in the harness between the combination meter and auto A/C control module.
8 CHECK POOR CONTACT. Check poor contact of auto A/C control module connector.Is there poor contact in connector?Repair the connector.Replace the auto A/C control module.

DIAGNOSIS PROCEDURE

  1. Blower fan speed, air flow outlet and FRESH/RECIRC do not change after turning the AUTO switch to ON.
  2. Failure related to the in-vehicle sensor is indicated in self-diagnosis.

Scheme 140

Scheme 140: WIRING DIAGRAM
Scheme 140: WIRING DIAGRAM
StepCheckYesNo
1 CHECK IN-VEHICLE SENSOR. Turn the ignition switch to OFF. Remove the driver's side lower cover. Disconnect the connector from in-vehicle sensor. Measure the resistance between terminals of in-vehicle sensor. Terminals No. 1 - No. 2Is the resistance approximately 2.2 kohms at 25°C (77°F) ?Go to step 2 .Replace the in-vehicle sensor.
2 CHECK INPUT SIGNAL FOR IN-VEHICLE SENSOR. Turn the ignition switch to ON. Measure the voltage between in-vehicle sensor harness connector terminals. Connector & terminal (i55) No. 2 (+) - No. 1 (-)Is the voltage approx. 5 V?Go to step 6 .Go to step 3 .
3 CHECK AUTO A/C CONTROL MODULE OUTPUT SIGNAL. Turn the ignition switch to OFF. Remove the auto A/C control module. Turn the ignition switch to ON. Measure the voltage between connector terminals of auto A/C control module. Connector & terminal (i88) No. 17 (+) - (i88) No. 14 (-)Is the voltage approx. 5 V?Go to step 4 .Go to step 6 .
4 CHECK HARNESS BETWEEN AUTO A/C CONTROL MODULE AND IN-VEHICLE SENSOR. Turn the ignition switch to OFF. Disconnect the connector from the auto A/C control module. Measure the resistance of harness between auto A/C control module and in-vehicle sensor. Connector & terminal (i55) No. 2 - (i88) No. 17Is resistance less than 1 ohms?Go to step 5 .Repair the harness between auto A/C control module and in-vehicle sensor.
5 CHECK HARNESS BETWEEN AUTO A/C CONTROL MODULE AND IN-VEHICLE SENSOR. Measure the resistance of harness between auto A/C control module and in-vehicle sensor. Connector & terminal (i55) No. 1 - (i88) No. 14Is resistance less than 1 ohms?Go to step 6 .Repair the harness between auto A/C control module and in-vehicle sensor.
6 CHECK POOR CONTACT. Check poor contact of auto A/C control module connector.Is there poor contact in connector?Repair the connector.Replace the auto A/C control module.

DIAGNOSIS PROCEDURE

Scheme 141

Scheme 141: WIRING DIAGRAM
Scheme 141: WIRING DIAGRAM
StepCheckYesNo
1 CHECK EVAPORATOR SENSOR. Turn the ignition switch to OFF. Remove the glove box. Disconnect the connector from evaporator sensor. Measure the resistance between terminals of the evaporator sensor. Terminals No. 1 - No. 2Is resistance approximately 6.2 kohms at 0°C (32°F), or approximately 3.3 kohms at 15°C (59°F) ?Go to step 2 .Replace the evaporator sensor.
2 CHECK INPUT SIGNAL FOR EVAPORATOR SENSOR. Turn the ignition switch to ON. Measure the voltage between connector (B88) terminals. Connector & terminal (B88) No. 1 (+) - No. 2 (-)Is the voltage approx. 5 V?Go to step 6 .Go to step 3 .
3 CHECK AUTO A/C CONTROL MODULE OUTPUT SIGNAL. Turn the ignition switch to OFF. Remove the auto A/C control module. Turn the ignition switch to ON. Measure the voltage between connector terminals of auto A/C control module. Connector & terminal (i88) No. 18 (+) - (i88) No. 14 (-)Is the voltage approx. 5 V?Go to step 4 .Go to step 6 .
4 CHECK HARNESS CONNECTOR BETWEEN AUTO A/C CONTROL MODULE AND EVAPORATOR SENSOR. Turn the ignition switch to OFF. Disconnect the connector from the auto A/C control module. Measure the resistance of harness between auto A/C control module and evaporator sensor. Connector & terminal (B88) No. 2 - (i88) No. 18Is the resistance less than 1 ohms?Go to step 5 .Repair the open circuit of harness between auto A/C control module and evaporator sensor.
5 CHECK HARNESS CONNECTOR BETWEEN AUTO A/C CONTROL MODULE AND EVAPORATOR SENSOR. Measure the resistance of harness between auto A/C control module and evaporator sensor. Connector & terminal (B88) No. 1 - (i88) No. 14Is the resistance less than 1 ohms?Go to step 6 .Repair the open circuit of harness between auto A/C control module and evaporator sensor.
6 CHECK POOR CONTACT. Check poor contact of auto A/C control module connector.Is there poor contact in connector?Repair the connector.Replace the auto A/C control module.

DIAGNOSIS PROCEDURE

  1. Sensor identifies that sunlight is at maximum. Then, A/C system is controlled to COOL side.
  2. Sensor identifies that sunlight is at minimum. Then, A/C system is controlled to HOT side.

Note. When the sunload sensor check is performed indoors or in the shade, it could be diagnosed as having an open circuit. Always check the sunload sensor with the sun shining on it.

Scheme 142

Scheme 142: WIRING DIAGRAM
Scheme 142: WIRING DIAGRAM
StepCheckYesNo
1 CHECK POWER SUPPLY VOLTAGE FOR SUNLOAD SENSOR. Turn the ignition switch to OFF. Disconnect the connector from sunload sensor. Turn the ignition switch to ON. Measure the power supply voltage for sun-load sensor. Connector & terminal (i51) No. 2 (+) - No. 1 (-)Is the voltage approx. 5 V?Go to step 4 .Go to step 2 .
2 CHECK HARNESS CONNECTOR BETWEEN AUTO A/C CONTROL MODULE AND SUN-LOAD SENSOR. Turn the ignition switch to OFF. Disconnect the connector from the auto A/C control module. Measure the resistance of the harness between the auto A/C control module and sun-load sensor. Connector & terminal (i51) No. 2 - (i88) No. 16Is resistance less than 1 ohms?Go to step 3 .Repair the harness between auto A/C control module and sunload sensor.
3 CHECK HARNESS CONNECTOR BETWEEN AUTO A/C CONTROL MODULE AND SUN-LOAD SENSOR. Measure the resistance of the harness between the auto A/C control module and sunload sensor. Connector & terminal (i51) No. 1 - (i88) No. 14Is resistance less than 1 ohms?Go to step 4 .Repair the harness between auto A/C control module and sunload sensor.
4 CHECK INPUT VOLTAGE FOR AUTO A/C CONTROL MODULE. Connect the connectors of sunload sensor and auto A/C control module. Turn the ignition switch to ON. Measure the voltage between connector terminals of auto A/C control module. Connector & terminal (i88) No. 16 (+) - (i88) No. 14 (-)Is the voltage within approximately 1.0 - 4.0 V?Go to step 5 .Replace the sunload sensor.
5 CHECK POOR CONTACT. Check poor contact of auto A/C control module connector.Is there poor contact in connector?Repair the connector.Replace the auto A/C control module.

DIAGNOSIS PROCEDURE

SymptomsProblem parts
A/C system fails to operate.Fuse (M/B No. 8, F/B No. 22, 31) Connector (Poor contact) Ground Auto A/C control module Blower fan motor Blower fan relay A/C relay Compressor (Magnet clutch) Evaporator sensor
Fuse is blown out.Fuse (M/B No. 8, F/B No. 22, 31) Connector (Poor contact)
Illumination cannot dim.Fuse (M/B No. 8, F/B No. 22, 31) Connector (Poor contact) Auto A/C control module
Blower fan does not rotate or fan speed cannot be controlled.Fuse (M/B No. 8, F/B No. 22,31) Connector (Poor contact) Ground Auto A/C control module Blower fan motor Blower fan relay
Unable to switch suction vents.Connector (Poor contact) Auto A/C control module Intake door actuator
Unable to switch vents.Connector (Poor contact) Auto A/C control module Mode door actuator
Room temperature does not rise (Warm air does not come out).Connector (Poor contact) Auto A/C control module Air mix door actuator In-vehicle sensor, ambient sensor, evaporator sensor and sunload sensor In-vehicle sensor aspirator hose
Room temperature does not lower (Cold air does not come out).Connector (Poor contact) Auto A/C control module Air mix door actuator A/C relay Compressor (Magnet clutch) Radiator fan motor Radiator fan relay In-vehicle sensor, ambient sensor, evaporator sensor and sunload sensor In-vehicle sensor aspirator hose
Compartment temperature is higher or lower than setting temperature.Auto A/C control module Air mix door actuator In-vehicle sensor, ambient sensor, evaporator sensor and sunload sensor In-vehicle sensor aspirator hose
Compartment temperature does not quickly respond to setting temperature.Air mix door actuator In-vehicle sensor, ambient sensor, evaporator sensor and sunload sensor In-vehicle sensor aspirator hose
Radiator fan does not rotate during A/C operation.Radiator fan motor Radiator fan relay

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