AIR CONDITIONING SYSTEM (for Manual Air Conditioning System), Diagnostic DTC:B1423

DTC Code DTC Name
B1423 Pressure Sensor Circuit

DESCRIPTION

This DTC is stored when refrigerant pressure is extremely low (0.176 MPa [1.8 kgf/cm2, 25.5 psi] or less) or extremely high (3.025 MPa [30.9 kgf/cm2, 438.6 psi] or higher). The air conditioner pressure sensor, which is installed on the pipe of the high pressure side to detect refrigerant pressure, outputs the refrigerant pressure signal to the air conditioning amplifier assembly. The air conditioning amplifier assembly converts the signal to a pressure value 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 may also be stored if there is no refrigerant in the cycle.

DTC Code DTC Detection Condition Trouble Area
B1423

Either condition is met:


  • An open or short in the air conditioner pressure sensor circuit.

  • Refrigerant pressure on the high pressure side is extremely low or extremely high.

  • Air conditioner pressure sensor

  • Harness or connector

  • Cooler expansion valve

  • Cooler condenser assembly

  • Cooler dryer

  • Refrigerant pipe line

  • Air conditioning amplifier assembly

WIRING DIAGRAM

A01DUNIE21

INSPECTION PROCEDURE

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (PRESSURE SENSOR - BATTERY AND BODY GROUND)


    1. A01DMOAE13
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Air Conditioning Pressure Sensor)

      Disconnect the A2 sensor connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A2-3 (+) - Body ground Ignition switch ON 4.75 to 5.25 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A2-1 (-) - Body ground Always Below 1 Ω

    NG

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

    OK

  2. CHECK AIR CONDITIONER PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)


    1. A01DTIYE09
      Text in Illustration
      *a

      Component with harness connected

      (Air Conditioning Amplifier Assembly)

      Reconnect the A2 sensor connector.

    2. Remove the air conditioning amplifier assembly with its connectors still connected Click here.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      G25-9 (PRE) - Body ground

      Ignition switch ON

      A/C switch off

      		 0.63 to 4.72 V

      Tech Tips

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


    NG

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

    OK

  3. CHECK AIR CONDITIONER PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)


    1. A01DTIYE09
      Text in Illustration
      *a

      Component with harness connected

      (Air Conditioning Amplifier Assembly)

      Measure the voltage when the following conditions are met.

      Measurement Condition
      Item Condition
      Engine Speed 2000 rpm
      Vehicle Doors Fully open
      Temperature Setting MAX COOL
      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 (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 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.

        Standard Voltage
        Tester Connection Switch Condition Specified Condition
        G25-9 (PRE) - Body ground

        Ignition switch ON

        A/C switch on

        		 0.63 to 4.72 V
        Result
        Result Proceed to
        OK (When troubleshooting according to problem symptoms table) A
        OK (When troubleshooting according to the DTC) B
        NG C

    B

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    C

    CHARGE REFRIGERANT Click here

    A

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

  4. CHECK HARNESS AND CONNECTOR (PRESSURE SENSOR - AIR CONDITIONING AMPLIFIER)


    1. Disconnect the G25 amplifier connector.

    2. Disconnect the A2 sensor connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A2-1 (-) - G25-13 (SG-2) Always Below 1 Ω
      A2-3 (+) - G25-10 (S5-3) Always Below 1 Ω
      G25-13 (SG-2) - Body ground Always 10 kΩ or higher
      G25-10 (S5-3) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

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


    1. Disconnect the G25 amplifier connector.

    2. Disconnect the A2 sensor connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A2-2 (PR) - G25-9 (PRE) Always Below 1 Ω
      G25-9 (PRE) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. CHECK FOR AIR CONDITIONING SYSTEM LEAK


    1. Install a 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 AIR CONDITIONING SYSTEM LEAK Click here

    OK

  7. CHARGE REFRIGERANT


    1. Add an appropriate amount of refrigerant Click here.


    NEXT

  8. CHECK FOR DTC


    1. Check for DTCs when the following conditions are met Click here.

      Measurement Condition
      Item Condition
      Engine Speed 2000 rpm
      Vehicle Doors Fully open
      Temperature Setting MAX COOL
      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, a DTC will be stored. Therefore, it is necessary to check for DTCs after a certain amount of time (approximately 10 minutes) has passed because the DTC may be stored after the air conditioning system 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 evaporator temperature sensor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.

      OK
      DTC B1423 is not output.

      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 leakage. Therefore, identify and repair the area where refrigerant leaks as necessary. The root cause of excessive refrigerant may be adding too much refrigerant.


    NG

    CHECK AIR CONDITIONER PRESSURE SENSOR Click here

    OK

    END (AMOUNT OF REFRIGERANT IS FAULTY)

  9. CHECK AIR CONDITIONER PRESSURE SENSOR


    1. A01DTIYE12
      Text in Illustration
      *a

      Component with harness connected

      (Air Conditioning Amplifier Assembly)

      Install a manifold gauge set.

    2. Reconnect the A2 sensor connector.

    3. Remove the air conditioning amplifier assembly with its connectors still connected Click here.

    4. Turn the ignition switch to ON.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      G25-9 (PRE) - G25-13 (SG-2)

      • Ignition switch ON

      • Refrigerant pressure normal (below 3.025 MPa [30.9 kgf/cm2, 438.6 psi] and higher than 0.176 MPa [1.8 kgf/cm2, 25.5 psi])

      		 0.63 to 4.72 V

      • Ignition switch ON

      • Refrigerant pressure abnormal (below 0.176 MPa [1.8 kgf/cm2, 25.5 psi])

      		 Below 0.63 V

      • Ignition switch ON

      • Refrigerant pressure abnormal (higher than 3.025 MPa [30.9 kgf/cm2, 438.6 psi])

      		 4.72 V or higher

    NG

    REPLACE AIR CONDITIONER PRESSURE SENSOR Click here

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

  10. REPAIR AIR CONDITIONING SYSTEM LEAK


    1. Identify the area where refrigerant leaks Click here.

    2. Repair the identified area of the air conditioning system.

    3. Evacuate the air conditioning system.


    NEXT

    CHARGE REFRIGERANT Click here

  11. 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 then check for the DTC.


    NEXT

  12. CHECK FOR DTC


    1. Check for DTCs when the following conditions are met Click here.

      Measurement Condition
      Item Condition
      Engine Speed 2000 rpm
      Vehicle Doors Fully open
      Temperature Setting MAX COOL
      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, a DTC will be stored. Therefore, it is necessary to check for DTCs after a certain amount of time (approximately 10 minutes) has passed because the DTC may be stored after the air conditioning system 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 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 cooler condenser assembly 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.

      OK
      DTC B1423 is not output.

    NG

    REPLACE COOLER EXPANSION VALVE Click here

    OK

    REPLACE COOLER DRYER Click here

  13. REPLACE COOLER EXPANSION VALVE


    1. Replace the cooler expansion valve with a new or normally functioning one Click here.

      Tech Tips

      Replace the cooler expansion valve with a new or normally functioning one because the cooler expansion valve is either stuck or clogged.


    NEXT

  14. CHARGE REFRIGERANT


    1. Add an appropriate amount of refrigerant Click here.


    NEXT

  15. CHECK FOR DTC


    1. Check for DTCs when the following conditions are met.

      Measurement Condition
      Item Condition
      Engine Speed 2000 rpm
      Vehicle Doors Fully open
      Temperature Setting MAX COOL
      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, a DTC will be stored. Therefore, it is necessary to check for DTCs after a certain amount of time (approximately 10 minutes) has passed because the DTC may be stored after the air conditioning system 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 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 normally functioning one, the cooler condenser assembly or pipes may be clogged due to dirt, dust or other contaminants. In this case, clean or replace the cooler condenser assembly or pipes.

      OK
      DTC B1423 is not output.

    NG

    CLEAN OR REPLACE COOLER CONDENSER ASSEMBLY OR PIPES Click here

    OK

    END (COOLER EXPANSION VALVE IS FAULTY)