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HVAC System (Auto AC) (Diagnostics): Diagnosis Subaru Outback BR

Automatic HVAC System 14 illustrations ~888 words

INSPECTION

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

A/C CONTROL SYSTEM SELF-DIAGNOSIS

StepCheckYesNo
1 SET SELF-DIAGNOSIS MODE BY OPERATING A/C CONTROL PANEL. Turn the ignition switch to OFF. Start the engine while holding down the AUTO switch and FRESH/RECIRC switch. NOTE: Self-diagnosis can also be performed with ignition switch ON, but start the engine because observing the compressor operation is difficult. All the indicators blink four times.Does the self-diagnosis function operate?Go to step 2 .Ref. to A/C OR SELF-DIAGNOSIS SYSTEMS DO NOT OPERATE , Diagnostics for A/C System Malfunction.
2 CHECK EACH SENSOR AND POTENTIOMETER. After the indicators stop blinking, automatically change to the Inspection Mode of sensor and potentiometer. NOTE: Display items can be changed each time the A/C switch is pressed. (Step Operation) When malfunction occurs in each sensor and potentiometer, codes are displayed on the screen. When no malfunction occurs in each sensor and potentiometer, code "20" is displayed on the screen. Identify defective sensors according to the sensor check table. Ref. to SENSOR CHECK TABLE , OPERATION, Diagnostic Chart for Self-Diagnosis.Are other codes except "20" displayed?Repair the defective sensor.Go to step 3 .
3 CHECK EACH ACTUATOR, BLOWER FAN AND COMPRESSOR. After completing each sensor and potentiometer inspection, change to the Inspection Mode of actuator, blower fan and compressor by pressing the defroster switch. Each mode will change and operate automatically every four seconds. NOTE: Operation mode items can be changed each time the A/C switch is pressed. (Step Operation) Check the operation of actuator, blower fan and compressor in each mode according to the operating mode table. Ref. to OPERATING MODE TABLE , OPERATION, Diagnostic Chart for Self-Diagnosis.Do the actuator, blower fan and compressor operate as described in the operating mode table?A/C control system is normal. Press the OFF switch and complete the self-diagnosis function.Repair the defective part in accordance with each diagnostic chart. Ref. to DIAGNOSTICS FOR A/C SYSTEM MALFUNCTION .
NOTE
Self-diagnosis can also be performed with ignition switch ON, but start the engine because observing the compressor operation is difficult.
NOTE
Display items can be changed each time the A/C switch is pressed. (Step Operation)
NOTE
Operation mode items can be changed each time the A/C switch is pressed. (Step Operation)

DIAGNOSTIC PROCEDURE

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 1

Scheme 1: WIRING DIAGRAM
Scheme 1: 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. 12 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 PANEL POWER CIRCUIT. Remove the A/C control panel. Disconnect the A/C control panel harness connector. Turn the ignition switch to ACC, and measure the voltage between A/C control panel harness connector terminal and chassis ground. Connector & terminal (i88) No. 5 (+) - 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 PANEL 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. 6 (+) - 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. 12 - Chassis groundIs the resistance less than 10 ohms?Go to step 6 .Repair the harness for ground line.
6 CHECK A/C CONTROL MODULE POWER CIRCUIT. Measure the voltage between A/C control module connector terminal and chassis ground after turning the ignition switch to OFF. Connector & terminal (i80) No. 1 (+) - Chassis ground (-)Is the voltage 10 V or more?Go to step 7 .Check for open or short circuit in the harness between A/C control module and fuse.
7 CHECK A/C CONTROL MODULE POWER CIRCUIT. Measure the voltage between A/C control module connector terminal and chassis ground after turning the ignition switch to ON. Connector & terminal (i80) No. 3 (+) - Chassis ground (-)Is the voltage 10 V or more?Go to step 8 .Check for open or short circuit in the harness between A/C control module and fuse.
8 CHECK A/C CONTROL MODULE GROUND CIRCUIT. Measure the resistance of harness between A/C control module and chassis ground. Connector & terminal (i80) No. 6 - Chassis groundIs the resistance less than 5 ohms?Go to step 9 .Repair the harness for ground line.
9 CHECK COMMUNICATION CIRCUIT. Measure the resistance of harness between A/C control panel and A/C control module. Connector & terminal (i88) No. 10 - (i80) No. 10: (i88) No. 4 - (i80) No. 7Is the resistance less than 1 ohms?Go to step 10 .Repair the harness.
10 CHECK COMMUNICATION CIRCUIT HARNESS. Measure the resistance between communication circuit harness and chassis ground. Connector & terminal (i80) No. 18 - Chassis ground: (i80) No. 7 - Chassis groundIs the resistance 1 Mohms or more?Repair or replace the short circuit of the harness.Go to step 11 .
11 CHECK FOR POOR CONTACT. Check poor contact of A/C control module connector.Is there poor contact of connector?Repair the connector.Replace the A/C CM. Ref. to REMOVAL , Control Unit.

DIAGNOSTIC PROCEDURE

  1. Blower motor does not rotate.
  2. Blower motor does not rotate in "HI".

Scheme 2

Scheme 2: WIRING DIAGRAM
Scheme 2: WIRING DIAGRAM
StepCheckYesNo
1 CHECK FUSE. Remove fuse No. 22 and 7 from fuse & relay box, and fuse No. 4 and 5 from the main fuse box. Check the condition of fuse.Is any fuse blown out?Replace the fuse.Go to step 2 .
2 CHECK POWER SUPPLY FOR BLOWER MOTOR. Turn the ignition switch to ON. Turn the blower switch to ON. Measure the voltage between blower motor and chassis ground. Connector & terminal (i85) No. 2 (+) - Chassis ground (-)Is 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. Turn the ignition switch to OFF. Remove the blower motor relay. Connect battery terminals to the blower motor relay. Terminals No. 2 - No. 4: Measure the resistance between terminals. Terminals No. 1 - No. 5Is the resistance less than 1 ohms?Go to step 4 .Replace the blower motor relay.
4 CHECK BLOWER MOTOR. Disconnect the connector from 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 5 .Replace the blower motor.
5 CHECK FOR POOR CONTACT. Check poor contact of A/C control module connector.Is there poor contact of connector?Repair the connector.Replace the A/C CM. Ref. to REMOVAL , Control Unit.

DIAGNOSTIC PROCEDURE

Scheme 3

Scheme 3: WIRING DIAGRAM
Scheme 3: WIRING DIAGRAM
StepCheckYesNo
1 CHECK DTC. Turn the ignition switch to ON. Read the DTC of the A/C system using the Subaru Select Monitor.Is DTC detected?Perform the diagnosis according to DTC.Go to step 2 .
2 CHECK AMOUNT OF REFRIGERANT. Check the refrigerant pressure. Ref. to PROCEDURE , Refrigerant Pressure with Manifold Gauge Set.Is the refrigerant pressure within the standard?Go to step 3 .Check and repair the refrigerant leakage.
3 CHECK POWER SUPPLY OF CONTROL MODULE. Disconnect the A/C CM connector. Turn the ignition switch to ON. Using a tester, measure the voltage between the connector terminal and chassis ground. Connector & terminal (i80) No. 2 (+) - Chassis ground (-)Is the voltage 10 V or more?Go to step 4 .Repair the defective power supply circuit.
4 CHECK CONTROL MODULE. Disconnect the compressor solenoid connector. Turn the ignition switch to ON. Using the tester, measure the voltage between terminals. Connector & terminal (i81) No. 2 - Chassis groundIs the voltage 10 V or more?Go to step 5 .Repair the defective harness.
5 CHECK HARNESS. Disconnect the A/C CM connector. Using a tester, check continuity between terminals. Connector & terminal (B506) No. 2 - (i181) No. 2Is there continuity?Go to step 6 .Repair or replace the open circuit.
6 CHECK GROUND. Using a tester, check the continuity between the connector terminal and chassis ground. Connector & terminal (B506) No. 1 - Chassis groundIs there continuity?Check the compressor solenoid.Repair or replace the open circuit.

DIAGNOSTIC PROCEDURE

Scheme 4

Scheme 4: WIRING DIAGRAM
Scheme 4: 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 2.2 kohms at 25°C (77°F)?Go to step 2 .Replace the ambient sensor. Ref. to REMOVAL , Ambient Sensor (Auto A/C Model).
2 CHECK INPUT SIGNAL FOR AMBIENT SENSOR. Turn the ignition to ON. Measure the voltage between connector (F138) terminals. Connector & terminal (F138) 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. 36 (+) - No. 37 (-)Is the voltage approx. 5 V?Go to step 4 .Go to step 6 .
4 CHECK HARNESS CONNECTOR BETWEEN COMBINATION METER AND AMBIENT SENSOR. Turn the ignition switch to OFF. Disconnect the connector from the combination meter. Measure the resistance of harness between combination meter and ambient sensor. Connector & terminal (F138) No. 2 - (i10) No. 36Is the resistance less than 10 ohms?Go to step 5 .Repair the open circuit of the harness between the combination meter and ambient sensor.
5 CHECK HARNESS CONNECTOR BETWEEN COMBINATION METER AND AMBIENT SENSOR. Measure the resistance of harness between combination meter and ambient sensor. Connector & terminal (F138) No. 2 - (i10) No. 36: (F138) No. 1 - (i10) No. 37Is the resistance less than 1 ohms?Go to step 6 .Repair the open circuit of the harness between the combination meter and ambient sensor.
6 CHECK DTC. Connect the disconnected connectors. Read the DTC of the CAN system using the Subaru Select Monitor.Is DTC for CAN system displayed?Perform the diagnosis according to DTC. Ref. to LIST OF DIAGNOSTIC TROUBLE CODE (DTC) .Go to step 7 .
7 CHECK CAN COMMUNICATION CIRCUIT. Check the CAN communication circuit. Ref. to CAN COMMUNICATION CIRCUIT CHECK .Is the CAN communication circuit normal?Go to step 8 .Repair the CAN communication circuit. Ref. to LAN SYSTEM , CAUTION, General Description.
8 CHECK FOR POOR CONTACT. Check poor contact of A/C CM connector.Is there poor contact of connector?Repair the connector.Replace the A/C CM. Ref. to REMOVAL , Control Unit.

DIAGNOSTIC PROCEDURE

DIAGNOSIS

Defective CAN communication circuit

  1. LAN system is abnormal.
  2. Communication failure between Subaru Select Monitor and A/C CM DIAGNOSTIC PROCEDURE Step Check Yes No 1 CHECK POWER SUPPLY CIRCUIT. Connect SDI (Subaru Diagnosis Interface) to the data link connector. Is SDI powered on? Go to step 4 . Go to step 2 . 2 CHECK POWER SUPPLY CIRCUIT.. Measure the voltage between data link connector and chassis ground. Connector & terminal (B40) No. 16 (+) - Chassis ground (-): Is the voltage 10 V or more? Go to step 3 . Repair the power supply circuit. NOTE: In this case, repair the following items: Open or short circuit in the harness between the battery and data link connector Blown out of fuse (M/B No. 13) 3 CHECK HARNESS BETWEEN DATA LINK CONNECTOR AND CHASSIS GROUND. Turn the ignition switch to OFF. Measure the resistance of harness between data link connector and chassis ground. Connector & terminal (B40) No. 4 - Chassis ground: (B40) No. 5 - Chassis ground: Is the resistance less than 5 ohms? Repair the poor contact of data link connector. Repair the harness and connector. 4 CHECK SUBARU SELECT MONITOR. Connect the Subaru Select Monitor to a normal vehicle. Start the engine and perform communication between the Subaru Select Monitor and vehicle. Is communication possible? Go to step 5 . Use another Subaru Select Monitor because the CAN communication circuit of the Subaru Select Monitor is faulty. 5 CHECK CAN COMMUNICATION CIRCUIT. Check the CAN communication circuit. Ref. to «OPERATION»(ref-371925-S08158969762010091900000) , Read Diagnostic Trouble Code (DTC). Is the CAN communication circuit normal? Check the connection between the data link connector and Subaru Select Monitor. Repair the CAN communication circuit.

DTC DETECTING CONDITION

In-vehicle sensor circuit is shorted.

  1. Auto A/C does not operate. (Manual operation is possible)
  2. In-vehicle temperature is falsely recognized as high, and the compartment temperature is adjusted.

Scheme 5

Scheme 5: WIRING DIAGRAM
Scheme 5: WIRING DIAGRAM
StepCheckYesNo
1 CHECK CURRENT DATA. Using the Subaru Select Monitor, check "In-vehicle Sensor Temperature" of the current data from the A/C diagnosis.Is the current data exceeding 25°C (77°F)?Go to step 2 .Check the connection of the in-vehicle sensor circuit.
2 CHECK IN-VEHICLE SENSOR. Disconnect the in-vehicle sensor. Ref. to REMOVAL , In-Vehicle Sensor (Auto A/C Model). Using the Subaru Select Monitor, check "In-vehicle Sensor Temperature" of the current data from the A/C diagnosis.Is the current data exceeding 25°C (77°F)?Go to step 3 .Replace the in-vehicle sensor. Ref. to REMOVAL , In-Vehicle Sensor (Auto A/C Model).
3 CHECK HARNESS. Turn the ignition switch to ON. Using the tester, measure the voltage between terminals. Connector & terminal (i173) No. 1 - No. 2Is the voltage 4.5 - 5.0 V?Check the connection of the in-vehicle sensor circuit.Go to step 4 .
4 CHECK HARNESS. Disconnect the connector from A/C CM. Using a tester, check continuity between terminals. Connector & terminal (i173) No. 1 - No. 2Is there continuity?Repair or replace the short circuit of the harness.Replace the A/C CM. Ref. to REMOVAL , Control Unit.

DIAGNOSTIC PROCEDURE

In-vehicle sensor circuit is open.

In-vehicle air temperature is falsely recognized as 25°C (77°F), and the compartment temperature is adjusted.

Evaporator sensor circuit is shorted.

  1. Compressor does not operate.
  2. Evaporator temperature is falsely recognized as high, and the compartment temperature is adjusted.

Scheme 6

Scheme 6: WIRING DIAGRAM
Scheme 6: WIRING DIAGRAM
StepCheckYesNo
1 CHECK CURRENT DATA. Using the Subaru Select Monitor, check "Evaporator Temperature" of the current data from the A/C diagnosis.Is the current data exceeding 50°C (90°F)?Go to step 2 .Check the connection of the evaporator sensor circuit.
2 CHECK EVAPORATOR SENSOR. Disconnect the evaporator sensor. Using the Subaru Select Monitor, check "Evaporator Temperature" of the current data from the A/C diagnosis.Is the current data exceeding 50°C (90°F)?Go to step 3 .Replace the evaporator sensor. Ref. to REMOVAL , Evaporator.
3 CHECK HARNESS. Turn the ignition switch to ON. Using the tester, measure the voltage between terminals. Connector & terminal (i172) No. 1 - No. 2Is the voltage 4.5 - 5.0 V?Check the connection of the evaporator sensor circuit.Go to step 4 .
4 CHECK HARNESS. Disconnect the connector from A/C CM. Using a tester, check continuity between terminals. Connector & terminal (i172) No. 1 - No. 2Is there continuity?Repair or replace the short circuit of the harness.Replace the A/C CM. Ref. to REMOVAL , Control Unit.

DIAGNOSTIC PROCEDURE

Evaporator sensor circuit is open.

Compressor does not operate.

Refrigerant pressure sensor circuit is open.

Compressor does not operate.

Scheme 7

Scheme 7: WIRING DIAGRAM
Scheme 7: WIRING DIAGRAM
StepCheckYesNo
1 CHECK CURRENT DATA. Using the Subaru Select Monitor, check "Refrigerant Pressure" of the current data from the A/C diagnosis.Does the current data display 3.19 MPa?Go to step 2 .Check the connection of the refrigerant pressure sensor circuit.
2 CHECK PRESSURE SENSOR. Disconnect the pressure sensor. Short No. 2 and No. 3 of B505 connector. Using the Subaru Select Monitor, check "Refrigerant Pressure" of the current data from the A/C diagnosis.Does the current data display 3.19 MPa?Go to step 3 .Replace the refrigerant pressure sensor. Ref. to REMOVAL , Evaporator.
3 CHECK HARNESS. Turn the ignition switch to ON. Using the tester, measure the voltage between terminals. Connector & terminal (B505) No. 1 - No. 3Is the voltage 4.5 - 5.0 V?Go to step 4 .Repair or replace the open circuit of harness.
4 CHECK HARNESS. Disconnect the connector from A/C CM. Using a tester, check continuity between terminals. Connector & terminal (B505) No. 1 - (i81) No. 1: (B505) No. 2 - (i80) No. 22: (B505) No. 3 - (i80) No. 16Is there continuity?Replace the A/C CM. Ref. to REMOVAL , Control Unit.Repair or replace the open circuit of harness.

DIAGNOSTIC PROCEDURE

Refrigerant pressure sensor circuit is shorted.

Compressor does not operate.

Sunload sensor circuit is shorted.

Control is performed as no sunload.

Scheme 8

Scheme 8: WIRING DIAGRAM
Scheme 8: WIRING DIAGRAM
StepCheckYesNo
1 CHECK CURRENT DATA. Using the Subaru Select Monitor, check "Quantity of Sunload" of the current data from the A/C diagnosis.Does the current data display 0 W/m 2 ?Go to step 2 .Check the connection of the sunload sensor circuit.
2 CHECK SUNLOAD SENSOR. Disconnect the sunload sensor. Short the i51 connector. Using the Subaru Select Monitor, check "Quantity of Sunload" of the current data from the A/C diagnosis.Does the current data display 0 W/m 2 ?Go to step 3 .Replace the sunload sensor. Ref. to REMOVAL , Evaporator.
3 CHECK HARNESS. Turn the ignition switch to ON. Using the tester, measure the voltage between terminals. Connector & terminal (i51) No. 1 - No. 2Is the voltage 4.5 - 5.0 V?Check the connection of the sunload sensor circuit.Go to step 4 .
4 CHECK HARNESS. Disconnect the connector from A/C CM. Using a tester, check continuity between terminals. Connector & terminal (i51) No. 1 - (i80) No. 16: (i51) No. 1 - (i80) No. 23Is there continuity?Repair or replace the short circuit of the harness.Replace the A/C CM. Ref. to REMOVAL , Control Unit.

DIAGNOSTIC PROCEDURE

Sunload sensor circuit is open. (Displayed for current malfunction)

Control is performed as no sunload.

Air mix door actuator - potentiometer circuit is open.

  1. Temperature cannot be adjusted.
  2. Temperature of the driver's dual air conditioner cannot be adjusted.

Scheme 9

Scheme 9: WIRING DIAGRAM
Scheme 9: WIRING DIAGRAM
StepCheckYesNo
1 CHECK CONNECTOR. Check the condition of connector connection. Read the DTC of the A/C CM using the Subaru Select Monitor.Is B1610 displayed?Go to step 2 .Repair poor contact of the air mix door actuator circuit.
2 CHECK ACTUATOR. Disconnect the air mix door actuator (driver's). Short No. 1 and No. 5 of i174 connector. Read the DTC of the A/C CM using the Subaru Select Monitor.Is B1611 displayed?Replace the air mix door actuator (driver's). Ref. to REMOVAL , Heater and Cooling Unit.Go to step 3 .
3 CHECK HARNESS. Disconnect the connector from A/C CM. Using a tester, check continuity between terminals. Connector & terminal (i174) No. 1 - (i80) No. 16: (i174) No. 3 - (i81) No. 1: (i174) No. 5 - (i80) No. 14Is there continuity?Go to step 4 .Repair or replace the open circuit of harness.
4 CHECK HARNESS. Using a tester, check continuity between terminals. Connector & terminal (i174) No. 1 - (i174) No. 3: (i174) No. 3 - (i174) No. 5: (i174) No. 5 - (i174) No. 1Is there continuity?Repair or replace the open circuit of harness.Replace the A/C CM. Ref. to REMOVAL , Control Unit.

DIAGNOSTIC PROCEDURE

Air mix door actuator - potentiometer circuit is shorted.

  1. Temperature cannot be adjusted.
  2. Temperature of the driver's dual air conditioner cannot be adjusted.
  1. Air mix door actuator - driver's seat is locked.
  2. The potentiometer value of the actuator does not change.

Temperature of the driver's dual air conditioner cannot be adjusted.

Air mix door actuator - potentiometer circuit is open.

Temperature of the passenger's dual air conditioner cannot be adjusted.

Scheme 10

Scheme 10: WIRING DIAGRAM
Scheme 10: WIRING DIAGRAM
StepCheckYesNo
1 CHECK CONNECTOR. Check the condition of connector connection. Read the DTC of the A/C CM using the Subaru Select Monitor.Is B1613 displayed?Go to step 2 .Repair the poor contact of connector.
2 CHECK ACTUATOR. Disconnect the air mix door actuator (passenger's). Short No. 3 and No. 5 of i175 connector. Read the DTC of the A/C CM using the Subaru Select Monitor.Is B1614 displayed?Go to step 3 .Replace the air mix door actuator (passenger's). Ref. to REMOVAL , Heater and Cooling Unit.
3 CHECK HARNESS. Disconnect the connector from A/C CM. Using a tester, check continuity between terminals. Connector & terminal (i175) No. 1 - (i181) No. 1: (i175) No. 3 - (i80) No. 16: (i175) No. 5 - (i80) No. 25Is there continuity?Go to step 4 .Repair or replace the open circuit of harness.
4 CHECK HARNESS. Using a tester, check continuity between terminals. Connector & terminal (i175) No. 1 - (i175) No. 3: (i175) No. 3 - (i175) No. 5: (i175) No. 5 - (i175) No. 1Is there continuity?Repair or replace the open circuit of harness.Replace the A/C CM. Ref. to REMOVAL , Control Unit.

DIAGNOSTIC PROCEDURE

Air mix door actuator - potentiometer circuit is shorted.

Temperature of the passenger's dual air conditioner cannot be adjusted.

  1. Passenger's air mix door actuator is locked.
  2. The potentiometer value of the actuator does not change.

Temperature of the passenger's dual air conditioner cannot be adjusted.

  1. Mode door does not move.
  2. The potentiometer value of the actuator does not change.

Vent does not change.

Scheme 11

Scheme 11: WIRING DIAGRAM
Scheme 11: WIRING DIAGRAM
StepCheckYesNo
1 CHECK CONNECTOR. Check the condition of connector connection. Read the DTC of the A/C CM using the Subaru Select Monitor.Is B1620 displayed?Go to step 2 .Repair the poor contact of connector.
2 CHECK ACTUATOR. Disconnect the mode door actuator. Short No. 2 and No. 3 of (i176) connector. Read the DTC of the A/C CM using the Subaru Select Monitor.Is B1621 displayed?Replace the mode door actuator. Ref. to REMOVAL , Heater and Cooling Unit.Go to step 3 .
3 CHECK HARNESS. Disconnect the connector from A/C CM. Using the tester, measure the voltage between terminals. Connector & terminal (i176) No. 1 - (i80) No. 16: (i176) No. 2 - (i181) No. 1: (i176) No. 3 - (i80) No. 26Is the voltage 4.5 - 5.0 V?Go to step 4 .Repair the open circuit of harness.
4 CHECK HARNESS. Using a tester, check continuity between terminals. Connector & terminal (i176) No. 1 - (i176) No. 2: (i176) No. 2 - (i176) No. 3: (i176) No. 3 - (i176) No. 1Is there continuity?Repair or replace the short circuit of the harness.Replace the A/C CM. Ref. to REMOVAL , Control Unit.

DIAGNOSTIC PROCEDURE

  1. Mode door does not move.
  2. The potentiometer value of the actuator does not change.

Vent does not change.

  1. Mode door does not move.
  2. The potentiometer value of the actuator does not change.

Vent does not change.

  1. Heater and A/C do not operate.
  2. A/C panel display does not change even though being operated.

Unable to operate A/C.

Scheme 12

Scheme 12: WIRING DIAGRAM
Scheme 12: WIRING DIAGRAM
StepCheckYesNo
1 CHECK HARNESS. Disconnect the connector from A/C control panel and A/C CM. Using a tester, check for continuity between the harness terminals. Connector & terminal (i80) No. 18 - (i88) No. 10: (i80) No. 7 - (i88) No. 4Is there continuity?Go to step 2 .Repair or replace the open circuit of harness.
2 CHECK HARNESS. Using a tester, check continuity between terminals. Connector & terminal (i80) No. 18 - No. 7Is there continuity?Repair or replace the short circuit of the harness.Replace the A/C CM. Ref. to REMOVAL , Control Unit.

DIAGNOSTIC PROCEDURE

  1. Data to be received via CAN communication do not arrive.
  2. A/C cooperation control does not operate.

A/C does not operate fully automatically.

StepCheckYesNo
1 CHECK DTC. Read the DTC of the CAN system using the Subaru Select Monitor.Is a DTC of the CAN system detected?Perform the diagnosis according to DTC.Go to step 2 .
2 CHECK A/C CM. Replace with a normally operating A/C CM. Read the DTC of the A/C system using the Subaru Select Monitor.Is U0001 detected?Go to step 3 .Replace the A/C CM. Ref. to REMOVAL , Control Unit.
3 CHECK CAN COMMUNICATION CIRCUIT. Check the CAN communication circuit. Ref. to LIST , CAN Communication Circuit Check.Is the CAN communication circuit normal?It is possible that temporary poor communication occurs. Clear the memory.Repair or replace the CAN communication circuit.

DIAGNOSTIC PROCEDURE

  1. Data to be received via CAN communication do not arrive.
  2. A/C cooperation control does not operate.

A/C does not operate fully automatically.

StepCheckYesNo
1 CHECK CURRENT DATA. Read the DTC of the CAN system using the Subaru Select Monitor.Is a DTC of the CAN system detected?Perform the diagnosis according to DTC.Go to step 2 .
2 CHECK A/C CM. Replace with a normally operating A/C CM. Read the DTC of the A/C system using the Subaru Select Monitor.Is U0002 detected?Go to step 3 .Replace the A/C CM. Ref. to REMOVAL , Control Unit.
3 CHECK CAN COMMUNICATION CIRCUIT. Check the CAN communication circuit. Ref. to LIST , CAN Communication Circuit Check.Is the CAN communication circuit normal?It is possible that temporary poor communication occurs. Clear the memory.Repair or replace the CAN communication circuit.

DIAGNOSTIC PROCEDURE

  1. The voltage of the sensor signal line decreased to 0.3 V or less.
  2. The circuit is open or shorted.

A/C does not function because refrigerant flow amount cannot be measured.

Scheme 13

Scheme 13: WIRING DIAGRAM
Scheme 13: WIRING DIAGRAM
StepCheckYesNo
1 CHECK SENSOR POWER SUPPLY. Disconnect the refrigerant flow sensor connector. Turn the ignition switch to ON. Using the tester, measure the voltage between terminals. Connector & terminal (B507) No. 1 - No. 2Is the voltage 4.5 - 5.0 V?Go to step 5 .Go to step 2 .
2 CHECK HARNESS. Disconnect the A/C CM connector. Using a tester, check continuity between terminals. Connector & terminal (B507) No. 3 - (i80) No. 13: (B507) No. 2 - (i181) No. 1: (B507) No. 1 - (i80) No. 16Is there continuity?Go to step 3 .Repair or replace the open circuit of harness.
3 CHECK HARNESS. Using a tester, check continuity between terminals. Connector & terminal (B507) No. 1 - Chassis ground: (B507) No. 2 - Chassis ground: (B507) No. 3 - Chassis groundIs there continuity?Repair or replace the short circuit of the harness.Go to step 4 .
4 CHECK HARNESS. Using a tester, check continuity between terminals. Connector & terminal (B507) No. 1 - No. 2: (B507) No. 1 - No. 3: (B507) No. 2 - No. 3Is there continuity?Repair or replace the short circuit of the harness.Go to step 5 .
5 CHECK A/C CM. Replace the A/C CM with a normal part. Read the DTC using Subaru Select Monitor.Is B1641 detected?Replace refrigerant flow sensor.Replace the A/C CM. Ref. to REMOVAL , Control Unit.

DIAGNOSTIC PROCEDURE

  1. The voltage of the sensor signal line increased to 4.7 V or more.
  2. The circuit is open or shorted.

A/C does not function because refrigerant flow amount cannot be measured.

  1. A/C does not operate.
  2. Refrigerant pressure does not increase or decrease.

Refrigerant pressure cannot be changed.

Scheme 14

Scheme 14: WIRING DIAGRAM
Scheme 14: WIRING DIAGRAM
StepCheckYesNo
1 ACTIVE TEST. Attach the manifold gauge. Using the Subaru Select Monitor, change the setting of "Variable Solenoid Output Duty" from the A/C diagnosis and perform the active test.Did the actuator operate to the specified target, and the pressure change?Variable flow change solenoid circuit is normal.Go to step 2 .
2 CHECK VARIABLE FLOW CHANGE SOLENOID. Disconnect the variable flow change solenoid connector. Using a tester, measure the resistance of the solenoid. Connector & terminal (B506) No. 1 - No. 2Is the resistance between 10 - 12 ohms?Go to step 3 .Replace the variable flow change solenoid. Ref. to REMOVAL , Heater and Cooling Unit.
3 CHECK HARNESS. Disconnect the A/C CM connector. Using a tester, check for continuity between the harness terminals. Connector & terminal (B506) No. 2 - (i181) No. 2: (B506) No. 1 - Chassis groundIs there continuity?Go to step 4 .Repair or replace the open circuit of harness.
4 CHECK HARNESS. Using a tester, check continuity between terminals. Connector & terminal (B506) No. 2 - Chassis groundIs there continuity?Repair or replace the short circuit of the harness.Replace the A/C CM. Ref. to REMOVAL , Control Unit.

DIAGNOSTIC PROCEDURE

  1. Compressor was operated while refrigerant was low.
  2. Compressor was operated while refrigerant pressure was extremely low.

A/C does not operate.

SymptomsProblem parts
A/C system fails to operate.Fuse Connector (Poor contact) Ground A/C control module Blower fan motor Blower fan relay A/C relay Compressor Compressor variable solenoid Evaporator sensor
Fuse is blown out.Fuse Connector (Poor contact) Harness shorted
Illumination cannot dim.Fuse Connector (Poor contact) A/C control module
Blower fan does not rotate or fan speed cannot be controlled.Fuse Connector (Poor contact) Ground A/C control module Blower fan motor Blower fan relay
Unable to switch suction vents.Connector (Poor contact) A/C control module Intake door actuator
Unable to switch vents.Connector (Poor contact) A/C control module Mode door actuator
Compartment temperature does not rise. (Warm air does not come out.)Connector (Poor contact) 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 lower. (Cold air does not come out.)Connector (Poor contact) A/C control module Air mix door actuator A/C relay Compressor Compressor variable solenoid 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.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

SYMPTOMS CHART

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