AIR CONDITIONING SYSTEM, Diagnostic DTC:B1423/23

DTC Code DTC Name
B1423/23 Pressure Sensor Circuit

DESCRIPTION

This DTC is stored when refrigerant pressure on the high pressure side is extremely low (0.19 MPa (2.0 kgf/cm2, 28 psi) or less) or extremely high (3.14 MPa (32.0 kgf/cm2, 455 psi) or more). The A/C pressure sensor is installed on the high pressure line. It detects refrigerant pressure to output a refrigerant pressure signal to the A/C amplifier. The A/C amplifier converts this signal to a pressure value according to the sensor characteristics to control the compressor.

DTC No. DTC Detection Condition Trouble Area
B1423/23

  • Open or short in pressure sensor circuit

  • Refrigerant pressure on the high pressure line is extremely low (0.19 MPa (2.0 kgf/cm2, 28 psi) or less) or extremely high (3.14 MPa (32.0 kgf/cm2, 455 psi) or more).

  • A/C pressure sensor

  • Harness or connector between A/C pressure sensor and A/C amplifier

  • A/C amplifier

  • Expansion valve (blocked, stuck)

  • Condenser (blocked, deterioration of cooling capacity due to dirt)

  • Cooler dryer (moisture in the refrigerant cycle cannot be absorbed)

  • Cooling fan system (condenser cannot be cooled down)

  • A/C system (leaks, blocked)

WIRING DIAGRAM

A01NG8YE10

INSPECTION PROCEDURE

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)


    1. A01NCY3E80
      Text in Illustration
      *1

      Front view of wire harness connector

      (to A/C Pressure Sensor)

      Disconnect the A/C pressure sensor connector.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A7-3 (+) - Body ground Power switch on (IG) 4.75 to 5.25 V

    NG

    CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER - A/C PRESSURE SENSOR) Click here

    OK

  2. CHECK HARNESS AND CONNECTOR (GROUND CIRCUIT)


    1. A01NCY3E81
      Text in Illustration
      *1

      Front view of wire harness connector

      (to A/C Pressure Sensor)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A7-1 (-) - Body ground Always Below 1 Ω

    NG

    CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER - A/C PRESSURE SENSOR) Click here

    OK

  3. INSPECT A/C PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)


    1. Reconnect the A/C pressure sensor connector.

    2. A01NGJVE88
      Text in Illustration
      *1

      Component with harness connected

      (A/C Amplifier)

      Remove the A/C amplifier with the connectors still connected.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      F50-9 (PRE) - Body ground

      Power switch on (IG)

      (A/C switch: off)

      		 0.73 to 4.84 V

      Tech Tips

      If the voltage is not as specified, there may be a malfunction in the A/C amplifier, A/C pressure sensor or wire harness. It is also possible that the amount of refrigerant may not be appropriate.


    NG

    CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER - A/C PRESSURE SENSOR) Click here

    OK

  4. INSPECT A/C PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)


    1. Measure the voltage when the following conditions are met:

      Item Condition
      Vehicle Doors Fully open
      Compressor speed 5200 rpm
      Temperature Setting MAX COLD
      Blower Speed HI
      A/C Switch on
      R/F Switch RECIRCULATION
      Interior Temperature 25 to 35°C (77 to 95°F)

      Note


      • If refrigerant pressure on the high pressure line becomes extremely high during the inspection (if the voltage exceeds 4.84 V), the fail-safe function stops compressor operation. Therefore, measure the voltage before the fail-safe function operates.

      • It is necessary to measure the voltage over a period of time (approximately 10 minutes) because the problem symptom may recur after a while.

      Tech Tips

      When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to signals from the ambient temperature sensor and the evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.


      1. A01NGJVE88
        Text in Illustration
        *1

        Component with harness connected

        (A/C Amplifier)

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

        Standard Voltage
        Tester Connection Condition Specified Condition
        F50-9 (PRE) - Body ground

        Power switch on (IG)

        (A/C: on)

        		 0.73 to 4.84 V
        Result
        Result Proceed to
        OK (When troubleshooting according to the DTC) A
        OK (When troubleshooting according to Problem Symptoms Table) B
        NG C

    B

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

    C

    INSPECT COOLING FAN SYSTEM Click here

    A

    REPLACE A/C AMPLIFIER Click here

  5. CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER - A/C PRESSURE SENSOR)


    1. A01NDH4E25

      Disconnect the A/C amplifier connector.

    2. A01NCY3E82
      Text in Illustration
      *1

      Front view of wire harness connector

      (to A/C Amplifier)
      *2

      Front view of wire harness connector

      (to A/C Pressure Sensor)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A7-3 (+) - F50-10 (S5-3) Always Below 1 Ω
      F50-10 (S5-3) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE A/C AMPLIFIER Click here

  6. CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER - A/C PRESSURE SENSOR)


    1. A01NDH4E26

      Disconnect the A/C amplifier connector.

    2. A01NCY3E83
      Text in Illustration
      *1

      Front view of wire harness connector

      (to A/C Amplifier)
      *2

      Front view of wire harness connector

      (to A/C Pressure Sensor)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A7-1 (-) - F50-13 (SG-2) Always Below 1 Ω
      F50-13 (SG-2) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE A/C AMPLIFIER Click here

  7. CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER - A/C PRESSURE SENSOR)


    1. A01NDH4E27

      Disconnect the A/C amplifier connector.

    2. A01NCY3E84
      Text in Illustration
      *1

      Front view of wire harness connector

      (to A/C Amplifier)
      *2

      Front view of wire harness connector

      (to A/C Pressure Sensor)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A7-2 (PR) - F50-9 (PRE) Always Below 1 Ω
      F50-9 (PRE) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  8. CHECK FOR A/C SYSTEM LEAK


    1. Install the manifold gauge set.

    2. Recover the refrigerant from the A/C system using a refrigerant recovery unit.

    3. Evacuate the A/C system and check that vacuum can be maintained.

      OK
      Vacuum can be maintained in the A/C system.

      Tech Tips

      If vacuum cannot be maintained in the A/C system, there may be a refrigerant leak. In this case, it is necessary to repair or replace the leaking part of the A/C system.


    NG

    REPAIR A/C SYSTEM LEAK Click here

    OK

  9. CHARGE REFRIGERANT


    1. Add an appropriate amount of refrigerant Click here.


    NEXT

  10. RECHECK FOR DTC


    1. Recheck for the DTC when the following conditions are met:

      Item Condition
      Vehicle Doors Fully open
      Compressor speed 5200 rpm
      Temperature Setting MAX COLD
      Blower Speed HI
      A/C Switch on
      R/F Switch RECIRCULATION
      Interior Temperature 25 to 35°C (77 to 95°F)

      Note

      If refrigerant pressure on the high pressure line is excessive, this DTC will be stored. Therefore, it is necessary to measure the voltage over a period of time (approximately 10 minutes) because this DTC may be stored after the A/C has been operating for a while.

      Tech Tips

      When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to signals from the ambient temperature sensor and the evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.

      Result
      Result Proceed to
      DTC B1423/23 is output A
      DTC B1423/23 is not output B

      Note

      If the DTC was stored due to an insufficient or excessive amount of refrigerant, the problem may have been solved after performing the previous step. However, the root cause of insufficient refrigerant may be refrigerant leaks. The root cause of excessive refrigerant may be adding refrigerant when the level was insufficient. Therefore, identify and repair any refrigerant leaks as necessary.


    B

    END

    A

  11. INSPECT A/C PRESSURE SENSOR


    1. Install the manifold gauge set.

    2. Reconnect the A/C pressure sensor connector.

    3. Turn the power switch on (IG).

    4. A01NGV8E05
      Text in Illustration
      *1

      Component with harness connected

      (A/C Amplifier)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      F50-9 (PRE) - F50-13 (SG-2)

      Refrigerant pressure:

      Normal pressure (less than 3.187 MPa [462 psi] and more than 0.39 MPa [57 psi])

      		 1.0 to 4.912 V

    NG

    REPLACE A/C PRESSURE SENSOR Click here

    OK

    REPLACE A/C AMPLIFIER Click here

  12. REPAIR A/C SYSTEM LEAK


    1. Identify the area where refrigerant leaks from Click here.

    2. Repair the identified area of the A/C system.

    3. Evacuate the A/C system.


    NEXT

    CHARGE REFRIGERANT Click here

  13. INSPECT COOLING FAN SYSTEM


    1. Check that the cooling fan(s) operates normally.

      Tech Tips

      Refer to Cooling Fan Circuit Click here.


    NG

    REPAIR COOLING FAN SYSTEM

    OK

  14. CHARGE REFRIGERANT


    1. Use a refrigerant recovery unit to recover refrigerant.

    2. Evacuate the A/C system.

    3. Add an appropriate amount of refrigerant Click here.

      Tech Tips

      If refrigerant is added and the system has not been properly evacuated (insufficient vacuum time), moisture in the air remaining in the system will freeze in the expansion valve, blocking the flow on the high pressure side. Therefore, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant, and check for DTCs.


    NEXT

  15. RECHECK FOR DTC


    1. Recheck for the DTC when the following conditions are met:

      Item Condition
      Vehicle Doors Fully open
      Compressor speed 5200 rpm
      Temperature Setting MAX COLD
      Blower Speed HI
      A/C Switch on
      R/F Switch RECIRCULATION
      Interior Temperature 25 to 35°C (77 to 95°F)

      Note

      If refrigerant pressure on the high pressure line is excessive, this DTC will be stored. Therefore, it is necessary to measure the voltage over a period of time (approximately 10 minutes) because DTC may be stored after the A/C has been operating for a while.

      Tech Tips


      • When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to signals from the ambient temperature sensor and the evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.

      • If refrigerant is added and the system has not been properly evacuated (insufficient vacuum time), moisture in the air remaining in the system will freeze in the expansion valve, blocking the flow on the high pressure side. Therefore, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant, and check for the DTC. If the DTC is not output, it indicates that the cooler dryer in the condenser is not able to absorb moisture in the refrigerant. In this case, to complete the repair, it is necessary to replace the cooler dryer.

      Result
      Result Proceed to
      DTC B1423/23 is output A
      DTC B1423/23 is not output B

    B

    REPLACE COOLER DRYER Click here

    A

  16. REPLACE EXPANSION VALVE


    1. Replace the expansion valve with a new or a known good one Click here.

      Tech Tips

      Replace the expansion valve with a new or a known good one because the expansion valve is either stuck or clogged.


    NEXT

  17. CHARGE REFRIGERANT


    1. Add an appropriate amount of refrigerant Click here.


    NEXT

  18. RECHECK FOR DTC


    1. Recheck for the DTC when the following conditions are met:

      Item Condition
      Vehicle Doors Fully open
      Compressor speed 5200 rpm
      Temperature Setting MAX COLD
      Blower Speed HI
      A/C Switch on
      R/F Switch RECIRCULATION
      Interior Temperature 25 to 35°C (77 to 95°F)

      Note

      If refrigerant pressure on the high pressure line is excessive, this DTC will be stored. Therefore, it is necessary to measure the voltage over a period of time (approximately 10 minutes) because this DTC may be stored after the A/C has been operating for a while.

      Tech Tips


      • When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to signals from the ambient temperature sensor and the evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.

      • If refrigerant pressure is not normal after replacing the expansion valve with a new or a known good one, the condenser or pipes may be clogged with dirt, dust or other contaminants. In this case, clean or replace the condenser or pipes.

      Result
      Result Proceed to
      DTC B1423/23 is not output A
      DTC B1423/23 is output B

    B

    REPLACE CONDENSER Click here

    A

    END

  19. REPLACE A/C PRESSURE SENSOR


    1. Replace the A/C pressure sensor Click here.

      Tech Tips

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


    NEXT

  20. RECHECK FOR DTC


    1. Recheck for the DTC when the following conditions are met:

      Item Condition
      Vehicle Doors Fully open
      Compressor speed 5200 rpm
      Temperature Setting MAX COLD
      Blower Speed HI
      A/C Switch on
      R/F Switch RECIRCULATION
      Interior Temperature 25 to 35°C (77 to 95°F)

      Note

      If refrigerant pressure on the high pressure line is excessive, this DTC will be stored. Therefore, it is necessary to measure the voltage over a period of time (approximately 10 minutes) because this DTC may be stored after the A/C has been operating for a while.

      Tech Tips

      When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to signals from the ambient temperature sensor and the evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.

      Result
      Result Proceed to
      DTC B1423/23 is not output A
      DTC B1423/23 is output B

    B

    REPLACE A/C AMPLIFIER Click here

    A

    END