AIR CONDITIONING SYSTEM (for Automatic Air Conditioning System), Diagnostic DTC:B1423/23

DTC Code DTC Name
B1423/23 Pressure Sensor Circuit

DESCRIPTION

This DTC is output if refrigerant pressure on the high pressure side is extremely low (0.197 MPa (2.0 kgf/cm2, 28 psi) or less) or extremely high (3.03 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 a refrigerant pressure signal to the Air Conditioning amplifier. The Air Conditioning amplifier converts this signal to pressure 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 side is extremely low (0.197 MPa (2.0 kgf/cm2, 28 psi) or less) or extremely high (3.03 MPa (32.0 kgf/cm2, 455 psi) or more).

  • Pressure sensor

  • Harness or connector between pressure sensor and Air Conditioning amplifier

  • Air Conditioning 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)

  • Air Conditioning system (leaks, blocked)

WIRING DIAGRAM

A017EXVE04

INSPECTION PROCEDURE

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)


    1. A017FZ1E33

      Disconnect the connector from the A/C pressure sensor.

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

      Standard voltage
      Tester Connection Condition Specified Condition
      A11-3 (+) - Body ground Ignition switch on (IG) Approx. 5 V

    NG

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

    OK

  2. CHECK HARNESS AND CONNECTOR (GROUND CIRCUIT)


    1. A017FZ1E34

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

      Standard resistance
      Tester Connection Condition Specified Condition
      A11-1 (-) - Body ground Always Below 1 Ω

    NG

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

    OK

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


    1. Reconnect the connector to the A/C pressure sensor.

    2. A017BACE43

      Remove the Air Conditioning amplifier with connectors still connected.

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

      Standard voltage
      Tester Connection Condition Specified Condition
      D33-9 (PRE) - Body ground

      Ignition switch on (IG)

      (A/C: OFF)

      		 0.5 to 4.8 V

      Tech Tips

      If the measured voltage is not within the normal range, there may be a malfunction in the Air Conditioning 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 (AIR CONDITIONING 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 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)
      Engine Speed 2000 rpm

      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 sensor and the evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.


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

        A017BACE43
        Standard voltage
        Tester Connection Condition Specified Condition
        D33-9 (PRE) - Body ground

        Ignition switch on (IG)

        (A/C: ON)

        		 0.5 to 4.8 V
        Result
        Result Proceed to
        OK (When troubleshooting according to DTC) A
        OK (When troubleshooting according to PROBLEM SYMPTOMS TABLE) B
        NG C

    B

    PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    C

    INSPECT COOLING FAN SYSTEM Click here

    A

    REPAIR OR REPLACE HARNESS OR CONNECTOR

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


    1. A017BP9E90

      Disconnect the connector from the Air Conditioning amplifier.

    2. A017FZ1E35

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

      Standard resistance
      Tester Connection Condition Specified Condition
      A11-3 (+) - D33-10 (S5-3) Always Below 1 Ω
      D33-10 (S5-3) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE AIR CONDITIONING AMPLIFIER Click here

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


    1. A017BP9E91

      Disconnect the connector from the Air Conditioning amplifier.

    2. A017FZ1E36

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

      Standard resistance
      Tester Connection Condition Specified Condition
      A11-1 (-) - D33-13 (SG-2) Always Below 1 Ω
      D33-13 (SG-2) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE AIR CONDITIONING AMPLIFIER Click here

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


    1. A017BP9E92

      Disconnect the connector from the Air Conditioning amplifier.

    2. A017FZ1E37

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

      Standard resistance
      Tester Connection Condition Specified Condition
      A11-2 (PR) - D33-9 (PRE) Always Below 1 Ω
      D33-9 (PRE) - 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 Air Conditioning system using a refrigerant recovery unit.

    3. Evacuate the Air Conditioning system and check that vacuum can be maintained in it.

      OK
      Vacuum can be maintained in the Air Conditioning system.

      Tech Tips

      If vacuum cannot be maintained in the Air Conditioning system, refrigerant may be leaking from it. In this case, it is necessary to repair or replace the leaking part of the Air Conditioning 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)
      Engine Speed 2000 rpm

      Note

      If refrigerant pressure on the high pressure side becomes high, the DTC will be set. , 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 from as necessary.


    B

    END

    A

  11. INSPECT A/C PRESSURE SENSOR


    1. Install the manifold gauge set.

    2. Disconnect the connector from the A/C pressure sensor.

    3. A017ESFE13

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

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

    5. 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

    NG

    REPLACE A/C PRESSURE SENSOR Click here

    OK

    REPLACE AIR CONDITIONING 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 Air Conditioning system.

    3. Evacuate the A/C system.


    NEXT

    CHARGE REFRIGERANT Click here

  13. INSPECT COOLING FAN SYSTEM


    1. Check if that the cooling fan operates normally.

      Tech Tips



    NG

    REPAIR COOLING FAN SYSTEM

    OK

  14. CHARGE REFRIGERANT


    1. Use a refrigerant recovery unit to recover refrigerant.

    2. Evacuate the Air Conditioning 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)
      Engine Speed 2000 rpm

      Note

      If refrigerant pressure on the high pressure side becomes high, the DTC will be set. It is necessary to measure the voltage for a certain amount of time (approximately 10 minutes) because the DTC may be set after the Air Conditioning 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 work, it indicates that the cooler dryer in the condenser is not able to absorb moisture in the refrigerant cycle. In this case, in order 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 CONDENSER WITH 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

    CHARGE REFRIGERANT

  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 RECIRCULATING
      Interior Temperature 25 to 35°C (77 to 95°F)
      Engine Speed 2000 rpm

      Note

      If refrigerant pressure on the high pressure side becomes high, the DTC will be set. It is necessary to measure the voltage for a certain amount of time (approximately 10 minutes) because the DTC may be set after the Air Conditioning 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 foreign matter. 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

    B

    CLEAN ON CONDENSER OR PIPE Click here

    A

    END