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Home >> Lexus >> 2020 >> UX 200 Luxury >> Repair and Diagnosis >> External Pages >> Different car >> Section 60 (Air Conditioning System - Diagnostic Codes (1 Of 2) (Hybrid)) >> AIR CONDITIONING SYSTEM (for HV Model) >> DTC B1423: Open in Pressure Sensor Circuit / Abnormal Refrigerant Pressure [07/2022 - ] >> Procedure

DTC B1423: Open in Pressure Sensor Circuit / Abnormal Refrigerant Pressure [07/2022 - ]: Procedure

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2024 Lexus UX 250h, 2023 Lexus UX 250h, 2022 Lexus UX 250h, 2021 Lexus UX 250h, and 2020 Lexus UX 250h. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK REFRIGERANT PRESSURE 
    1. Connect the Techstream to the DLC3.
    2. Turn the power switch on (IG).
    3. Turn the Techstream on.
    4. Enter the following menus: Body Electrical / Air Conditioner / Data List.
    5. Read the Data List according to the display on the Techstream.

      Body Electrical > Air Conditioner > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Regulator Pressure Sensor Air conditioner pressure sensor Min.: -66.2 psi (gauge)
      Max.: 478.0 psi (gauge)      		 Actual refrigerant pressure displayed
      • Refrigerant line (gas leak etc.)
      • Air conditioner pressure sensor circuit malfunction

      Body Electrical > Air Conditioner > Data List 

      Tester Display
      Regulator Pressure Sensor
    6. Install a manifold gauge set.
      1. for HFO-1234yf(R1234yf):

        Refer to ON-VEHICLE INSPECTION [07/2022 - ]

      2. for HFO-1234yf(R1234yf):

        Refer to ON-VEHICLE INSPECTION [07/2022 - ]

    7. Read the manifold gauge set with the following conditions met.
      MEASUREMENT CONDITION:

      Item Condition
      Vehicle doors Fully open
      Temperature setting MAX COLD
      Blower speed HI
      A/C switch On
      Recirculation/fresh switch RECIRCULATION
      Interior temperature 25 to 35°C (77 to 95°F)

      Standard Pressure

      Low pressure side 

      150 to 250 kPa (1.5 to 2.5 kgf/cm2 , 22 to 36 psi)

      High pressure side 

      1370 to 1570 kPa (14 to 16 kgf/cm2 , 199 to 228 psi)

    8. Compare the values displayed in the Data List and on the manifold gauge set.

      OK

      The values displayed in the Data List and on the manifold gauge set match.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  7

    Result: 

    OK 

    See step  2

  2. CHECK REFRIGERANT HIGH PRESSURE HISTORY 
    1. Connect the Techstream to the DLC3.
    2. Turn the power switch on (IG).
    3. Enter the following menus: Body Electrical / Air Conditioner / Data List.
    4. Read the Data List according to the display on the Techstream.

      Body Electrical > Air Conditioner > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Refrigerant High Pressure History Refrigerant high pressure history Min.: 0
      Max.: 255      		 Number of times refrigerant high pressure history stored displayed -

      Body Electrical > Air Conditioner > Data List 

      Tester Display
      Refrigerant High Pressure History

      Result

      Result Proceed to
      The value is 0 A
      The value is not 0 B

    Result: 

    A 

    INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET 

    for HFC-134a(R134a): Refer to REPLACEMENT [07/2022 - ]

    for HFO-1234yf(R1234yf): Refer to REPLACEMENT [07/2022 - ]

    Result: 

    B 

    See step  3

  3. INSPECT COOLING FAN SYSTEM 
    1. Check if the cooling fan operates normally.

      Refer to ON-VEHICLE INSPECTION [10/2018 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    GO TO COOLING FAN SYSTEM. Refer to  Cooling Fan Circuit [10/2018 - ] 

    Result: 

    OK 

    See step  4

  4. RECOVER REFRIGERANT FROM REFRIGERATION SYSTEM 
    1. Recover the refrigerant from the air conditioning system using a refrigerant recovery unit.
      1. for HFC-134a(R134a):

        Refer to REPLACEMENT [07/2022 - ]

      2. for HFO-1234yf(R1234yf):

        Refer to REPLACEMENT [07/2022 - ]

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  5

  5. CHARGE AIR CONDITIONING SYSTEM WITH REFRIGERANT 
    1. for HFC-134a(R134a):

      Refer to REPLACEMENT [07/2022 - ]

    2. for HFO-1234yf(R1234yf):

      Refer to REPLACEMENT [07/2022 - ]

    Result

    Proceed to
    NEXT

    Result: 

    NEXT 

    See step  6

  6. PERFORM REFRIGERANT HIGH PRESSURE HISTORY CLEAR 
    1. Clear the refrigerant high pressure history stored in the air conditioning amplifier assembly.

      Refer to UTILITY [07/2022 - ]

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    END 

  7. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT) 
    GTY831811Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Front view of wire harness connector (to Air Conditioner Pressure Sensor)
    1. Disconnect the air conditioner pressure sensor connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      A25-3 (+) - Body ground Power switch on (IG) 4.75 to 5.25 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  12

    Result: 

    OK 

    See step  8

  8. CHECK HARNESS AND CONNECTOR (AIR CONDITIONER PRESSURE SENSOR - BODY GROUND) 
    1. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A25-1 (-) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  11

    Result: 

    OK 

    See step  9

  9. CHECK HARNESS AND CONNECTOR (AIR CONDITIONER PRESSURE SENSOR - AIR CONDITIONING AMPLIFIER ASSEMBLY) 
    1. Disconnect the F50 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
      A25-2 (PR) - F50-24 (PRE) Always Below 1 Ω
      A25-2 (PR) or F50-24 (PRE) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  10

  10. INSPECT AIR CONDITIONER PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT) 
    GTY779787Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Component with harness connected
    (Air Conditioning Amplifier Assembly)
    1. Connect all the connectors.
    2. Measure the voltage with the following conditions met.
      MEASUREMENT CONDITION:

      Item Condition
      Vehicle doors Fully open
      Temperature setting MAX COLD
      Blower speed HI
      A/C switch On
      Recirculation/fresh 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 4.61 V), a fail-safe function will stop compressor operation. In this case, make sure to measure the voltage before the fail-safe function operates.
      • It is necessary to measure the voltage for a certain amount of time (approximately 10 minutes) because the malfunction may recur after a while.

      HINT: 

      When the ambient air temperature is low(below -1.5°C (29.3°F)), the compressor with motor assembly will be stopped, due to inputs of the thermistor assembly and No. 1 cooler thermistor, 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
        F50-24 (PRE) - Body ground Power switch on (IG)
        (A/C switch: On)        		 0.74 to 4.61 V*

        *: While sensor voltage is 5 V.

    3. Connect the Techstream to the DLC3.
    4. Turn the power switch on (IG).
    5. Turn the Techstream on.
    6. Enter the following menus: Body Electrical / Air Conditioner / Data List.
    7. Read the Data List according to the display on the Techstream.

      Body Electrical > Air Conditioner > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Regulator Pressure Sensor Air conditioner pressure sensor Min.: -66.2 psi (gauge)
      Max.: 478.0 psi (gauge)      		 Actual refrigerant pressure displayed
      • Refrigerant line (gas leak etc.)
      • Air conditioner pressure sensor circuit malfunction

      Body Electrical > Air Conditioner > Data List 

      Tester Display
      Regulator Pressure Sensor

      OK

      The voltage and value displayed in the Data List change.

      Result

      Result Proceed to
      OK A
      NG (The voltage changes but the value displayed in the Data List does not change.)
      NG (The voltage does not change.) B

    Result: 

    A 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [07/2022 - ] 

    Result: 

    B 

    REPLACE AIR CONDITIONER PRESSURE SENSOR. Refer to  REMOVAL [10/2018 - ] 

  11. CHECK HARNESS AND CONNECTOR (AIR CONDITIONER PRESSURE SENSOR - AIR CONDITIONING AMPLIFIER ASSEMBLY) 
    1. Disconnect the F50 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
      A25-1 (-) - F50-3 (SG-4) Always Below 1 Ω
      A25-1 (-) or F50-3 (SG-4) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [07/2022 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  12. CHECK HARNESS AND CONNECTOR (AIR CONDITIONER PRESSURE SENSOR - AIR CONDITIONING AMPLIFIER ASSEMBLY) 
    1. Disconnect the F50 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
      A25-3 (+) - F50-6 (S5-3) Always Below 1 Ω
      A25-3 (+) or F50-6 (S5-3) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [07/2022 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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