AIR CONDITIONING SYSTEM (for Automatic Air Conditioning System), Diagnostic DTC:B1479/79

DTC Code DTC Name
B1479/79 Flow Sensor Circuit

DESCRIPTION

The A/C flow sensor, which is mounted on the compressor, is used to detect the amount of refrigerant flow. The A/C flow sensor converts the amount of refrigerant flow that is detected to a voltage value to send it to the air conditioning amplifier assembly. The voltage value sent from the A/C flow sensor changes depending on the amount of refrigerant flow. As the amount of refrigerant flow becomes larger, the voltage becomes lower. As the amount of refrigerant flow becomes smaller, the voltage becomes higher. The air conditioning amplifier assembly supplies 5 V to the A/C flow sensor and monitors changes in the voltage value sent from the A/C flow sensor. The air conditioning amplifier assembly then sends a signal to the ECM via CAN communication to allow the ECM to control the engine speed while the air conditioning is on.

DTC No. DTC Detection Condition Trouble Area
B1479/79 Open or short in A/C flow sensor circuit

  • Compressor assembly with pulley (A/C flow sensor)*1

  • Cooler compressor assembly (A/C flow sensor)*2

  • Harness or connector between compressor assembly with pulley (A/C flow sensor) and air conditioning amplifier assembly*1

  • Harness or connector between Cooler compressor assembly (A/C flow sensor) and air conditioning amplifier assembly*2

  • Air conditioning amplifier assembly

WIRING DIAGRAM

A011SJ8E20

INSPECTION PROCEDURE

PROCEDURE

  1. CONFIRM MODEL

    Result
    Result Proceed to
    for 2AR-FE A
    for 2GR-FE B
    B

    READ VALUE USING TECHSTREAM Click here

    A

  2. READ VALUE USING TECHSTREAM

    1. Connect the Techstream to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the Techstream on.

    4. Enter the following menus: Body Electrical / Air Conditioner / Data List.

    5. Check the value(s) by referring to the table below.

      Air Conditioner
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Flow Sensor

      A/C flow sensor /

      Min.: 0.0 V

      Max.: 5.0 V

      A/C on, Blower switch HI: 0.7 to 3.8 V

      A/C off, Blower switch off: 3.8 to 4.2 V

      		 A/C flow sensor is malfunctioning when a constant value between 0.7 and 4.2 V is displayed continuously for more than 4 seconds.
      OK
      The display is as specified in the Normal Condition column.
      Result
      Result Proceed to
      OK (When troubleshooting according to Problem Symptoms Table) A
      OK (When troubleshooting according to the DTC) B
      NG (When a constant value between 0.7 and 4.2 V is displayed continuously for more than 4 seconds) C
    B

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    C

    REPLACE COMPRESSOR ASSEMBLY WITH PULLEY (A/C FLOW SENSOR) Click here

    A

  3. READ VALUE USING TECHSTREAM

    1. Connect the Techstream to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the Techstream on.

    4. Enter the following menus: Body Electrical / Air Conditioner / Data List.

    5. Check the value(s) by referring to the table below.

      Air Conditioner
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      A/C Cutoff Signal

      A/C control cutoff signal /

      OFF or ON

      A/C switch on: OFF

      A/C switch off: ON

      		 -
      Result
      Result Proceed to
      Value in Data List indicates OFF A
      Value in Data List indicates ON B
    B

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    A

  4. REPLACE COMPRESSOR ASSEMBLY WITH PULLEY (A/C FLOW SENSOR)

    1. Replace the compressor assembly with pulley (A/C flow sensor) Click here (for 2AR-FE)).

      Tech Tips

      Since the compressor assembly with pulley (A/C flow sensor) cannot be inspected while it is removed from the vehicle, replace the compressor assembly with pulley (A/C flow sensor) with a new or a known good one and check that the condition returns to normal.

    2. Check for the DTC.

      Result
      Result Proceed to
      DTC B1479/79 is not output A
      DTC B1479/79 is output B
    B

    CHECK HARNESS AND CONNECTOR (COMPRESSOR ASSEMBLY WITH PULLEY (A/C FLOW SENSOR) - AIR CONDITIONING AMPLIFIER ASSEMBLY) Click here

    A

    END

  5. CHECK HARNESS AND CONNECTOR (COMPRESSOR ASSEMBLY WITH PULLEY (A/C FLOW SENSOR) - AIR CONDITIONING AMPLIFIER ASSEMBLY)

    1. Disconnect the I77 air conditioning amplifier assembly connector.

    2. Disconnect the E75 compressor assembly with pulley (A/C flow sensor) connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      I77-7 (FLOQ) - E75-3 (QUFL) Always Below 1 Ω
      I77-13 (SG-2) - E75-2 (SGFL) Always Below 1 Ω
      I77-30 (S5-1) - E75-1 (S5FL) Always Below 1 Ω
      I77-7 (FLOQ) - Body ground Always 10 kΩ or higher
      I77-13 (SG-2) - Body ground Always 10 kΩ or higher
      I77-30 (S5-1) - Body ground Always 10 kΩ or higher
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

  6. READ VALUE USING TECHSTREAM

    1. Connect the Techstream to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the Techstream on.

    4. Enter the following menus: Body Electrical / Air Conditioner / Data List.

    5. Check the value(s) by referring to the table below.

      Air Conditioner
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Flow Sensor

      A/C flow sensor /

      Min.: 0.0 V

      Max.: 5.0 V

      A/C on, Blower switch HI: 0.7 to 3.8 V

      A/C off, Blower switch off: 3.8 to 4.2 V

      		 A/C flow sensor is malfunctioning when a constant value between 0.7 and 4.2 V is displayed continuously for more than 4 seconds.
      OK
      The display is as specified in the Normal Condition column.
      Result
      Result Proceed to
      OK (When troubleshooting according to Problem Symptoms Table) A
      OK (When troubleshooting according to the DTC) B
      NG (When a constant value between 0.7 and 4.2 V is displayed continuously for more than 4 seconds) C
    B

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    C

    REPLACE COOLER COMPRESSOR ASSEMBLY (A/C FLOW SENSOR) Click here

    A

  7. READ VALUE USING TECHSTREAM

    1. Connect the Techstream to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the Techstream on.

    4. Enter the following menus: Body Electrical / Air Conditioner / Data List.

    5. Check the value(s) by referring to the table below.

      Air Conditioner
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      A/C Cutoff Signal

      A/C control cutoff signal /

      OFF or ON

      A/C switch on: OFF

      A/C switch off: ON

      		 -
      Result
      Result Proceed to
      Value in Data List indicates OFF A
      Value in Data List indicates ON B
    B

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    A

  8. REPLACE COOLER COMPRESSOR ASSEMBLY (A/C FLOW SENSOR)

    1. Replace the cooler compressor assembly (A/C flow sensor) Click here.

      Tech Tips

      Since the cooler compressor assembly (A/C flow sensor) cannot be inspected while it is removed from the vehicle, replace the cooler compressor assembly (A/C flow sensor) with a new or a known good one and check that the condition returns to normal.

    2. Check for the DTC.

      Result
      Result Proceed to
      DTC B1479/79 is not output A
      DTC B1479/79 is output B
    B

    CHECK HARNESS AND CONNECTOR (COOLER COMPRESSOR ASSEMBLY (A/C FLOW SENSOR) - AIR CONDITIONING AMPLIFIER ASSEMBLY) Click here

    A

    END

  9. CHECK HARNESS AND CONNECTOR (COOLER COMPRESSOR ASSEMBLY (A/C FLOW SENSOR) - AIR CONDITIONING AMPLIFIER ASSEMBLY)

    1. Disconnect the I77 air conditioning amplifier assembly connector.

    2. Disconnect the E75 cooler compressor assembly (A/C flow sensor) connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      I77-7 (FLOQ) - E75-3 (QUFL) Always Below 1 Ω
      I77-13 (SG-2) - E75-2 (SGFL) Always Below 1 Ω
      I77-30 (S5-1) - E75-1 (S5FL) Always Below 1 Ω
      I77-7 (FLOQ) - Body ground Always 10 kΩ or higher
      I77-13 (SG-2) - Body ground Always 10 kΩ or higher
      I77-30 (S5-1) - Body ground Always 10 kΩ or higher
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here