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 (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 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 (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).

  • 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)

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

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

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

  • A/C system (leaks, blocked)

WIRING DIAGRAM

A0004D6E29
*a Air Conditioning Pressure Sensor
*b Air Conditioning Amplifier Assembly

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)


    1. Disconnect the A47 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
      A47-3 (+) - Body ground Power switch on (IG) 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
      A47-1 (-) - 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 A47 air conditioning pressure sensor connector.

    2. A0006POE01
      Text in Illustration
      *a

      Component with harness connected

      (Air Conditioning Amplifier Assembly)

      Remove the air conditioning amplifier assembly 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
      H54-9 (PRE) - Body ground

      Power switch on (IG)

      (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. Turn the power switch on (READY).

    2. 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 4.80 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. A0006POE01
        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
        H54-9 (PRE) - Body ground

        Power switch on (IG)

        (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

    A

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    B

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

    C

    INSPECT COOLING FAN SYSTEM Click here

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


    1. Disconnect the H54 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
      A47-3 (+) - H54-10 (S5-3) Always Below 1 Ω
      H54-10 (S5-3) - Body ground Always 10 kΩ or higher

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

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


    1. Disconnect the H54 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
      A47-1 (-) - H54-13 (SG-2) Always Below 1 Ω
      H54-13 (SG-2) - Body ground Always 10 kΩ or higher

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

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


    1. Disconnect the H54 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
      A47-2 (PR) - H54-9 (PRE) Always Below 1 Ω
      H54-9 (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 cooler 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 DTCs.


    NEXT

  10. RECHECK FOR DTC


    1. Turn the power switch on (READY).

    2. Recheck for DTCs 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. 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 A47 air conditioning pressure sensor connector.

    3. Turn the power switch on (IG).

    4. A00056DE01
      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
      H54-9 (PRE) - H54-13 (SG-2)

      Refrigerant pressure:

      (less than 3025 kPa (30.9 kgf/cm2, 439 psi) and more than 176 kPa (1.8 kgf/cm2, 25 psi))

      		 0.50 to 4.80 V

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    NG

    REPLACE AIR CONDITIONING PRESSURE SENSOR 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.


    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 cooler 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 DTCs.


    NEXT

  15. RECHECK FOR DTC


    1. Turn the power switch on (READY).

    2. Recheck for DTCs 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. 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 cooler 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 DTCs. If DTCs are not output after this work, it indicates that the cooler dryer in the cooler condenser assembly 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 cooler 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 cooler 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 DTCs.


    NEXT

  18. RECHECK FOR DTC


    1. Turn the power switch on (READY).

    2. Recheck for DTCs 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. 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 cooler expansion valve with a normal one, the cooler condenser assembly or pipes may be clogged due to dirt, dust or other foreign matter. In this case, clean or replace the cooler condenser assembly or pipes.

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

    A

    END

    B

    CLEAN OR REPLACE COOLER CONDENSER ASSEMBLY OR PIPE