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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) >> Weak Blower Output [12/2019 - 10/2022] >> Procedure

Weak Blower Output [12/2019 - 10/2022]: Procedure

  1. CHECK MALFUNCTIONING AREA 
    1. Confirm the area where the blower airflow volume is low.

      Result

      Result Proceed to
      Front air conditioning unit A
      Rear air conditioning unit  B

    Result: 

    B 

    See step  6

    Result: 

    A 

    See step  2

  2. CHECK AIR CONDITIONING SYSTEM 
    1. Operate the blower switch with the following conditions met and check that the airflow volume changes.
      Blower Speed Condition
      LO → HI
      • Temperature setting: MAX COLD
      • Air outlet mode: FACE
      • A/C switch: Off

      OK

      Airflow volume increases.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    GO TO OTHER DIAGNOSIS PROCEDURE (Blower Motor Circuit). Refer to  Blower Motor Circuit [12/2019 - 10/2022]  

    Result: 

    OK 

    See step  3

  3. CHECK ECO MODE SETTING 
    1. Confirm that ECO drive mode is set to off.

      HINT: 

      When the ECO drive mode is set to ON, the air conditioning amplifier assembly performs minimal air conditioning control in order to promote the improvement of fuel economy. Ensure that the customer understands that the airflow volume will be decreased compared to normal operation.

      Control Control Summary
      Air Volume Control Sets the blower level to less.

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  4

  4. CHECK CLEAN AIR FILTER 
    1. Visually check the clean air filter.

      OK

      The clean air filter is not dirty or clogging.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE CLEAN AIR FILTER. Refer to  DISASSEMBLY [12/2019 - ] 

    Result: 

    OK 

    See step  5

  5. CHECK EVAPORATOR TEMP. SENSOR (NO. 1 COOLER THERMISTOR) 
    1. Check the installation condition of the evaporator temp. sensor (No. 1 cooler thermistor).

      OK

      Evaporator temp. sensor (No. 1 cooler thermistor) is installed correctly.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE HEATER RADIATOR UNIT SUB-ASSEMBLY OR NO. 1 COOLER EVAPORATOR SUB-ASSEMBLY. Refer to  REMOVAL [12/2019 - 10/2022] 

    Result: 

    NG 

    REINSTALL EVAPORATOR TEMP. SENSOR (NO. 1 COOLER THERMISTOR). Refer to  INSTALLATION [12/2019 - ] 

  6. CHECK AIR CONDITIONING SYSTEM 
    1. Operate the blower switch with the following conditions met and check that the airflow volume changes.
      Blower Speed Condition
      LO → HI
      • Temperature setting: MAX COLD
      • Air outlet mode: FACE
      • A/C switch: Off

      OK

      Airflow volume increases.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    GO TO OTHER DIAGNOSIS PROCEDURE (Rear Blower Motor Circuit). Refer to  Rear Blower Motor Circuit [12/2019 - 10/2022]  

    Result: 

    OK 

    See step  7

  7. CHECK ECO MODE SETTING 
    1. Confirm that ECO drive mode is set to off.

      HINT: 

      When the ECO drive mode is set to ON, the air conditioning amplifier assembly performs minimal air conditioning control in order to promote the improvement of fuel economy. Ensure that the customer understands that the airflow volume will be decreased compared to normal operation.

      Control Control Summary
      Air Volume Control Sets the blower level to less.

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    REPLACE REAR EVAPORATOR SUB-ASSEMBLY. Refer to  DISASSEMBLY [12/2019 - ] 

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