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 stored if refrigerant pressure on the high pressure side is extremely low (190 kPa (1.9 kgf/cm2, 28 psi) or less) or extremely high (3140 kPa (32.0 kgf/cm2, 455 psi) or more). The air conditioning pressure sensor, which is installed on the pipe on the high pressure side to detect refrigerant pressure, sends a refrigerant pressure signal to the air conditioning amplifier assembly. The air conditioning amplifier assembly converts this signal to a pressure value according to the sensor characteristics and uses it to control the compressor.

DTC No. DTC Detection Condition Trouble Area
B1423/23

  • Open or short in air conditioning pressure sensor circuit

  • Refrigerant pressure on the high pressure side is extremely low (190 kPa (1.9 kgf/cm2, 28 psi) or less) or extremely high (3140 kPa (32.0 kgf/cm2, 455 psi) or more).

  • Air conditioning pressure sensor

  • Harness or connector between air conditioning pressure sensor and air conditioning amplifier assembly

  • Air conditioning amplifier assembly

  • Cooler expansion valve (blocked, stuck)

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

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

  • Cooling fan system (condenser assembly cannot be cooled down)

  • A/C system (leaks, blocked)

WIRING DIAGRAM

A01HQT7E08

INSPECTION PROCEDURE

Tech Tips

If DTC B1423 and B14B8 are output at the same time, troubleshoot for DTC B1423 first.

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)


    1. Disconnect the A55 air conditioning pressure sensor connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A55-3 (+) - Body ground Ignition switch ON 4.75 to 5.25 V

    NG

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

    OK

  2. CHECK HARNESS AND CONNECTOR (GROUND CIRCUIT)


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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A55-1 (-) - Body ground Always Below 1 Ω

    NG

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

    OK

  3. INSPECT AIR CONDITIONING PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)


    1. Reconnect the A55 air conditioning pressure sensor connector.

    2. A01HP41E14
      Text in Illustration
      *a

      Component with harness connected

      (Air Conditioning Amplifier Assembly)

      Remove the air conditioning amplifier assembly with connectors still connected.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      I77-9 (PRE) - Body ground

      Ignition switch ON

      (A/C: off)

      		 0.50 to 4.80 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 conditioning 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 ASSEMBLY - AIR CONDITIONING PRESSURE SENSOR) Click here

    OK

  4. INSPECT AIR CONDITIONING 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. A01HP41E15
        Text in Illustration
        *a

        Component with harness connected

        (Air Conditioning Amplifier Assembly)

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

        Standard Voltage
        Tester Connection Condition Specified Condition
        I77-9 (PRE) - Body ground

        Ignition switch ON

        (A/C: on)

        		 0.50 to 4.80 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 AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

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


    1. Disconnect the I77 air conditioning amplifier assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A55-3 (+) - I77-10 (S5-3) Always Below 1 Ω
      I77-10 (S5-3) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

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


    1. Disconnect the I77 air conditioning amplifier assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A55-1 (-) - I77-13 (SG-2) Always Below 1 Ω
      I77-13 (SG-2) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

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


    1. Disconnect the I77 air conditioning amplifier assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A55-2 (PR) - I77-9 (PRE) Always Below 1 Ω
      I77-9 (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 a 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 SYSTEM WITH 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

  10. RECHECK FOR 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 B1423/23 is output A
      DTC B1423/23 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 AIR CONDITIONING PRESSURE SENSOR


    1. Install a manifold gauge set.

    2. Reconnect the air conditioning pressure sensor connector.

    3. Turn the ignition switch to ON.

    4. A01HP41E16
      Text in Illustration
      *a

      Component with harness connected

      (Air Conditioning Amplifier Assembly)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      I77-9 (PRE) - I77-13 (SG-2)

      Refrigerant pressure:

      (less than 3025 kPa (30.8 kgf/cm2, 439 psi) and more than 176 kPa (1.8 kgf/cm2, 26 psi))

      		 0.50 to 4.80 V

    NG

    REPLACE AIR CONDITIONING PRESSURE SENSOR Click here

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY 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 SYSTEM WITH REFRIGERANT Click here

  13. INSPECT COOLING FAN SYSTEM


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

      Tech Tips


      • Refer to cooling fan system Click here (for 2AR-FE)).

      • Refer to cooling fan system Click here (for 2GR-FE)).


    NG

    REPAIR COOLING FAN SYSTEM

    OK

  14. CHARGE SYSTEM WITH 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 FOR 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. It is necessary to replace the cooler dryer in order to complete the repair.

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

    B

    REPLACE COOLER CONDENSER ASSEMBLY Click here

    A

  16. REPLACE COOLER EXPANSION VALVE


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

      Tech Tips

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


    NEXT

  17. CHARGE SYSTEM WITH 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

  18. RECHECK FOR 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 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 B1423/23 is not output A
      DTC B1423/23 is output B

    B

    CLEAN OR REPLACE CONDENSER OR PIPE

    A

    END