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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Heating / Air Conditioning System (Except HV, W/ Manual A/C) - Diagnostic Codes, Circuit Tests & Symptom Tests >> AIR CONDITIONING SYSTEM (for Gasoline Model with Manual Air Conditioning System) >> DTC B14B8: Refrigerant Shortage [12/2019 - 10/2022] >> Procedure

DTC B14B8: Refrigerant Shortage [12/2019 - 10/2022]: Procedure

  1. CHECK REFRIGERANT PRESSURE 
    1. Install a manifold gauge set.

      Refer to ON-VEHICLE INSPECTION [12/2019 - ]

    2. Prepare the vehicle according to the table below.
      MEASUREMENT CONDITION:

      Item Condition
      Vehicle Condition Engine start
      Doors Fully closed (windows also fully closed)
      A/C Switch On
      Recirculation/fresh Control Switch Recirculation
      Set Temperature MAX COLD
      Blower Speed HI
      Air Conditioning Air Inlet Temperature 25 to 35°C (77 to 95°F)
    3. Read the manifold gauge pressure.

      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)

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

      Body Electrical > Air Conditioner > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Regulator Pressure Sensor Air conditioner pressure sensor Min.: -456.68 kPaG (gauge)
      Max.: 3294.37 kPaG (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 values displayed in the Data List and on the manifold gauge match.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET. Refer to  ON-VEHICLE INSPECTION [12/2019 - ] 

    Result: 

    NG 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (AIR CONDITIONER PRESSURE SENSOR - POWER SOURCE) 
    1. Disconnect the A24 air conditioner pressure sensor connector.
      GTY926230Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Air Conditioner Pressure Sensor)
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A24-3 (+) - Body ground Ignition switch ON 4.75 to 5.25 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  7

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (AIR CONDITIONER PRESSURE SENSOR - BODY GROUND) 
    1. Disconnect the A24 air conditioner pressure sensor connector.
      GTY926186Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Air Conditioner Pressure Sensor)
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A24-1 (-) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  6

    Result: 

    OK 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - AIR CONDITIONER PRESSURE SENSOR) 
    1. Disconnect the H63 air conditioning amplifier assembly connector.
    2. Disconnect the A24 air conditioner pressure sensor connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      H63-6 (PRE) - A24-2 (PR) Always Below 1 Ω
      H63-6 (PRE) or A24-2 (PR) - 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  5

  5. INSPECT AIR CONDITIONING AMPLIFIER ASSEMBLY (SENSOR SIGNAL CIRCUIT) 
    NOTE:
    • If refrigerant pressure on the high pressure side becomes extremely high during the inspection (if the voltage exceeds 4.61 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 malfunction may recur after a while.

    HINT: 

    When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to operation of the ambient temp. sensor (thermistor assembly) and the evaporator temp. sensor (No. 1 cooler thermistor) to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.

    1. Connect the H63 air conditioning amplifier assembly connector.
    2. Connect the A24 air conditioner pressure sensor connector.
    3. Prepare the vehicle according to the table below.
      MEASUREMENT CONDITION:

      Item Condition
      Vehicle Condition Engine start
      Doors Fully closed (windows also fully closed)
      A/C Switch On
      Recirculation/fresh Control Switch Recirculation
      Set Temperature MAX COLD
      Blower Speed HI
      Air Conditioning Air Inlet Temperature 25 to 35°C (77 to 95°F)
    4. Measure the voltage according to the value(s) in the table below.
      GTY886400Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Air Conditioning Amplifier Assembly)      		 - -

      Standard Voltage

      Tester Connection Condition Specified Condition
      H63-6 (PRE) - Body ground
      • Engine start
      • Air conditioning system operating
      • Sensor voltage is 5V
      		 0.74 to 4.61 V
    5. Read the Data List according to the display on the GTS.

      Body Electrical > Air Conditioner > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Regulator Pressure Sensor Air conditioner pressure sensor Min.: -456.68 kPaG (gauge)
      Max.: 3294.37 kPaG (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 [12/2019 - 10/2022] 

    Result: 

    B 

    REPLACE AIR CONDITIONER PRESSURE SENSOR. Refer to  REMOVAL [12/2019 - 10/2022] 

  6. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - AIR CONDITIONER PRESSURE SENSOR) 
    1. Disconnect the H63 air conditioning amplifier assembly connector.
    2. Disconnect the A24 air conditioner pressure sensor connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      H63-15 (SG-4) - A24-1 (-) Always Below 1 Ω
      H63-15 (SG-4) or A24-1 (-) - 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 [12/2019 - 10/2022] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  7. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - AIR CONDITIONER PRESSURE SENSOR) 
    1. Disconnect the H63 air conditioning amplifier assembly connector.
    2. Disconnect the A24 air conditioner pressure sensor connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      H63-11 (S5-3) - A24-3 (+) Always Below 1 Ω
      H63-11 (S5-3) or A24-3 (+) - 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 [12/2019 - 10/2022] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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