AIR CONDITIONING SYSTEM, Diagnostic DTC:B1423/23

DTC Code DTC Name
B1423/23 Pressure Sensor Circuit

DESCRIPTION

This DTC is output when refrigerant pressure 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 pressure sensor, which is installed on the pipe of the high pressure side to detect refrigerant pressure, outputs the refrigerant pressure signal to the front controller. The front controller sends the read signal to the air conditioning amplifier via the CAN communication line. The air conditioning amplifier converts the signal to pressure according to the sensor characteristics to control the compressor.

Tech Tips


  • Be sure to check the refrigerant volume first when this DTC is output because this DTC can also be output if there is no refrigerant in the cycle.

  • This circuit uses the CAN communication line. Before performing the inspection, check that the CAN communication system is functioning normally.

DTC Code DTC Detection Condition Trouble Area
B1423/23

  • Open or short in pressure sensor circuit

  • 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)

  • Pressure sensor

  • Harness or connector between pressure sensor and front controller

  • Front controller

  • 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)

  • Refrigerant pipe line

  • CAN communication line

  • Air conditioning amplifier

WIRING DIAGRAM

A000ZVGE05

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)


    1. A000V8ZE01
      *1 Front view of wire harness connector: (to Pressure Sensor)

      Disconnect the B4 pressure sensor connector.

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

      Standard voltage
      Tester Connection Condition Specified Condition
      B4-3 (+) - Body ground Power switch ON (IG) 4.4 to 5.5 V

    NG

    CHECK HARNESS AND CONNECTOR (FRONT CONTROLLER - PRESSURE SENSOR) Click here

    OK

  2. CHECK HARNESS AND CONNECTOR (GROUND CIRCUIT)


    1. A000V8ZE02
      *1 Front view of wire harness connector: (to Pressure Sensor)

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

      Standard resistance
      Tester Connection Condition Specified Condition
      B4-1 (-) - Body ground Always Below 1 Ω

    NG

    CHECK HARNESS AND CONNECTOR (FRONT CONTROLLER - PRESSURE SENSOR) Click here

    OK

  3. INSPECT PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)


    1. Reconnect the B4 pressure sensor connector.

    2. A000UJVE01
      *1 Component with harness connected: (Front Controller)
      *2 PRS

      Remove the front controller with its connectors still connected.

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

      Standard voltage
      Tester Connection Condition Specified Condition
      B14-13 (PRS) - Body ground

      Power switch ON (IG)

      A/C OFF

      		 0.7 to 4.8 V

      Tech Tips

      If the measured voltage is not within the normal range, there may be a malfunction in the front controller, pressure sensor, or wire harness. It is also possible that the amount of refrigerant may not be appropriate.


    NG

    CHECK HARNESS AND CONNECTOR (FRONT CONTROLLER - PRESSURE SENSOR) Click here

    OK

  4. INSPECT PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)


    1. Measure the voltage when the following conditions are satisfied.

      Item Condition
      Vehicle Doors Fully open
      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 side becomes extremely high during the inspection (if the voltage exceeds 4.8 V), the fail-safe function stops compressor operation. Therefore, measure the voltage before the fail-safe operation.

      • It is necessary to measure the voltage for a certain amount 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 operation of the ambient temperature and the evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.


      1. A000UJVE01
        *1 Component with harness connected: (Front Controller)
        *2 PRS

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

        Standard voltage
        Tester Connection Condition Specified Condition
        B14-13 (PRS) - Body ground

        Power switch ON (IG)

        A/C ON

        		 0.7 to 4.8 V

    OK

    REPLACE FRONT CONTROLLER

    NG

    INSPECT COOLING FAN SYSTEM Click here

  5. CHECK HARNESS AND CONNECTOR (FRONT CONTROLLER - PRESSURE SENSOR)


    1. Disconnect the B14 front controller connector.

      A000Y3OE06
      *1 Front view of wire harness connector: (to Pressure Sensor)
      *2 Front view of wire harness connector: (to Front Controller)

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

      Standard resistance
      Tester Connection Condition Specified Condition
      B4-3 (+) - B14-12 (S5) Always Below 1 Ω
      B14-12 (S5) - Body ground Always 10 kΩ or higher

    OK

    REPLACE FRONT CONTROLLER

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  6. CHECK HARNESS AND CONNECTOR (FRONT CONTROLLER - PRESSURE SENSOR)


    1. Disconnect the the B14 front controller connector.

      A000Y3OE07
      *1 Front view of wire harness connector: (to Pressure Sensor)
      *2 Front view of wire harness connector: (to Front Controller)

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

      Standard resistance
      Tester Connection Condition Specified Condition
      B4-1 (-) - B14-14 (SG) Always Below 1 Ω
      B14-14 (SG) - Body ground Always 10 kΩ or higher

    OK

    REPLACE FRONT CONTROLLER

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  7. CHECK HARNESS AND CONNECTOR (FRONT CONTROLLER - PRESSURE SENSOR)


    1. Disconnect the B14 front controller connector..

      A000Y3OE08
      *1 Front view of wire harness connector: (to Pressure Sensor)
      *2 Front view of wire harness connector: (to Front Controller)
      *3 PRS

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

      Standard resistance
      Tester Connection Condition Specified Condition
      B4-2 (PR) - B14-13 (PRS) Always Below 1 Ω
      B14-13 (PRS) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  8. INSPECT 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 in it.

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

      Tech Tips

      If vacuum cannot be maintained in the A/C system, refrigerant may be leaking from it. 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 DTC


    1. Recheck for the DTC when the following conditions are satisfied.

      Item Condition
      Vehicle Doors Fully open
      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 side becomes high, the DTC will be set. Therefore, it is necessary to measure the voltage for a certain amount of time (approximately 10 minutes) because the DTC may be set after the A/C operates for a while.

      Tech Tips

      When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to operation of 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 is output A
      DTC B1423 is not output B

      Note

      If the DTC was set 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 the area where refrigerant leaks as necessary.


    B

    END

    A

  11. INSPECT PRESSURE SENSOR


    1. Install the manifold gauge set.

    2. Disconnect the connector from the pressure sensor.

    3. Connect 3 1.5 V dry cell batteries in series.

    4. Connect 3 1.5 V dry cell batteries' positive (+) lead to terminal 3, and the negative (-) lead to terminal 1.

      A000TGVE01

    5. Connect the voltmeter's positive (+) lead to terminal 2, and the negative (-) lead to terminal 1.

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

      Standard voltage
      Tester Connection Condition Specified Condition
      2 - 1

      Refrigerant pressure:

      0.39 to 3.187 MPa (57 to 463 psi)

      		 1.0 to 4.8 V

    OK

    REPLACE FRONT CONTROLLER

    NG

    REPLACE PRESSURE SENSOR Click here

  12. REPAIR A/C SYSTEM LEAK


    1. Identify the area where refrigerant leaks 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. Inspect that the cooling fan operates normally Click here.


    NG

    REPAIR COOLING FAN SYSTEM Click here

    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, in order to confirm the problem, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant, and check for the DTC.


    NEXT

  15. RECHECK DTC


    1. Recheck for the DTC when the following conditions are satisfied.

      Item Condition
      Vehicle Doors Fully open
      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 side becomes high, the DTC will be set. Therefore, it is necessary to measure the voltage for a certain amount of time (approximately 10 minutes) because the DTC may be set after the A/C operates for a while.

      Tech Tips


      • When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to operation of 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, in order to confirm the problem, 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 after this procedure, it indicates that the cooler dryer in the condenser is not able to absorb moisture in the refrigerant cycle. In this case, to complete the repair it is necessary to replace the cooler dryer.

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

    B

    REPLACE COOLER DRYER Click here

    A

  16. REPLACE EXPANSION VALVE


    1. Replace the expansion valve with a normal one Click here.

      Tech Tips

      Replace the expansion valve with a normal 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 DTC


    1. Recheck for the DTC when the following conditions are satisfied.

      Item Condition
      Vehicle Doors Fully open
      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 side becomes high, the DTC will be set. Therefore, it is necessary to measure the voltage for a certain amount of time (approximately 10 minutes) because the DTC may be set after the A/C operates for a while.

      Tech Tips


      • When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to operation of 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 normal one, the condenser or pipes may be clogged due to dirt, dust or other contaminants. In this case, clean or replace the condenser or pipes.

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

    A

    END

    B

    REPLACE CONDENSER Click here