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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/ Auto A/C) - Diagnostics - Introduction >> AIR CONDITIONING SYSTEM (for Gasoline Model with Automatic Air Conditioning System) >> Problem Symptoms Table [12/2019 - 10/2022] >> Problem Symptoms Table [12/2019 - 10/2022]

Problem Symptoms Table [12/2019 - 10/2022]

NOTE:
  • Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, the potential causes of the symptoms are listed in order of probability in the "Suspected Area" column of the table. Check each symptom by checking the suspected areas in the order they are listed. Replace parts as necessary.
  • Inspect the fuses and relays related to this system before inspecting the suspected areas below.
  1. VEHICLE CHECK ITEMS 

    HINT: 

    • You can reduce the number of systems to check by using the results of the following operation check.
    • Perform the following checks based on Customer Feedback and the vehicle condition.
    • The customer's opinion may not be consistent with the actual problem (eg: the cooling performance of the air conditioner is bad → actually, the wind volume is weak). It is important to check the problem symptoms accurately and judge correctly based on various sources of information.
    • Judgment as to whether the air conditioner panel is normal or abnormal can be judged by checking if the indicator illuminates or turns off when the switch is operated.
    • During servo motor initialization, the AUTO indicator light comes on, and then turns off when initialization has finished.
    • If the performance of the air conditioner is poor or there is a foul odor, check for clogging in the clean air filter.

    Malfunction Operation/Function

    Common Function of Cool and Heater Function Only Cool Air Function Only Heater Function Suspected Area
    A/C Switch Operation Blower Operation Recirculation/Fresh Function Air Outlet Changing Function
    x o o o x x Go to "Problem Symptoms Table: Air Conditioning Control"
    o o o o x o Go to "Problem Symptoms Table: Cooling Function"
    o o o o o x Go to "Problem Symptoms Table: Heater Function"
    o x o o x x Go to "Problem Symptoms Table: Blower Control"
    o o x o x x Go to "Problem Symptoms Table: Air Inlet Control"
    o o o x x x Go to "Problem Symptoms Table: Air Outlet Control"
    x x x x x x Air Conditioning Amplifier Assembly or Air Conditioner Unit Assembly is Defective
  2. AIR CONDITIONING CONTROL 
    Symptom Suspected Area Link
    Air conditioning system cannot be operated using air conditioning control assembly
    1. (With the exception of the switch indicators, no inputs are reflected when other switches operated)
    • LIN communication malfunction between air conditioning amplifier assembly and air conditioning control assembly
    • LIN communication malfunction between air conditioning amplifier assembly and No. 2 air conditioning control assembly
    • Short to +B or ground in air conditioning amplifier assembly circuit
    • Air conditioning amplifier assembly malfunction
    • Air conditioning control assembly malfunction
    • Harness or connector
    Air conditioning system cannot be operated using air conditioning control assembly
    1. (Air conditioning system display operates)
    • Air conditioning control assembly
    • No. 2 air conditioning control assembly
    Air conditioning system cannot be operated using air conditioning control assembly immediately after starting the engine
    1. (Air conditioning system display operates) (Only AUTO indicator illuminates)

      (A/C switch indicator does not illuminate)

    		 Refer to "INITIALIZATION" Refer to INITIALIZATION [12/2019 - 11/2023] 
    A/C switch indicator does not illuminate
    • Air conditioning amplifier assembly malfunction
    • Air conditioning control assembly malfunction
    • A/C switch malfunction
    • A/C switch indicator malfunction (including when indicator turned off without switch operation)
    • Servo motor initialization (incomplete)
    • Mechanical locking of damper and damper link
    • Refrigerant pressure is extremely low
    • Low detected ambient temperature (including thermistor assembly malfunction)
    		 Refer to A/C Switch Indicator does not Turn On [12/2019 - 11/2023]
  3. COOLING FUNCTION 
    Symptom Suspected Area Link
    Cool air is not discharged
    1. (Air is discharged)
    • Compressor with pulley assembly malfunction
    • Refrigerant pressure malfunction
    • Lack of refrigerant gas
    • Dirty cooler condenser
    • Cooling fan system malfunction
    • Air mix damper and link operation (jamming)
    • Evaporator temperature sensor (determined as cold, but conflicts with actual temperature)
    • Warm air flow
    		 Refer to No Cooling at All [12/2019 - 11/2023]
    • Cooling effectiveness is poor
    • Cooling response is slow
    • ECO mode control of air conditioning system is enabled
    • Compressor with pulley assembly malfunction
    • Refrigerant volume (high)
    • Refrigerant volume (low)
    • Clogged cooler condenser assembly fins
    • Cooling fan system malfunction
    • Mechanical locking of damper and damper link
    • Automatic light control sensor malfunction
    • High inlet air temperature
    • Harness or connector
    		 Refer to Cooling is Poor [12/2019 - 10/2022]
    Temperature of outlet air is cooler on left or right side
    1. (When same temperature set for both sides)
    • Compressor with pulley assembly malfunction
    • Refrigerant volume (low)
    • Mechanical locking of damper and damper link
    • Automatic light control sensor malfunction
    • Harness or connector
    		 Refer to Air Vent Temperature does not Change and Right Vent is Different from Left and Vice Versa (Same Left/Right Temperature Setting) [12/2019 - 11/2023]
    • Cooler compressor assembly does not stop operating
    • Refrigerant pressure does not decrease when A/C switch is turned off
    • Short to +B in air conditioning amplifier assembly circuit malfunction
    • A/C COMP relay malfunction
    • Magnet clutch assembly malfunction
    • Harness or connector
    		 Refer to Air Conditioning Compressor Magnetic Clutch Circuit [12/2019 - 10/2022]
  4. HEATER FUNCTION 
    Symptom Suspected Area Link
    • No warm air comes out (Blower control is normal)
    • Outlet air temperature does not increase (Blower control is normal)
    • Engine coolant temperature (low)
    • Refrigerant volume (low)
    • Air mix damper and link operation (jamming)
    • Warm-up control
    • Blockage in heater radiator unit sub-assembly
    • Heater radiator unit sub-assembly malfunction
    • Flow shutting valve (water by-pass hose assembly) malfunction
    		 Refer to No Heating at All [12/2019 - 11/2023]
    Temperature of outlet air is warmer on left or right side
    1. (When same temperature set for both sides)
    • Mechanical locking of damper and damper link
    • Blockage in heater radiator unit sub-assembly
    • Harness or connector
    		 Refer to Air Vent Temperature does not Change and Right Vent is Different from Left and Vice Versa (Same Left/Right Temperature Setting) [12/2019 - 11/2023]
    w/ Quick Heater:
    Heating performance is poor when it is cold
    • Quick heater assembly malfunction
    • Air conditioning amplifier assembly malfunction
    • PTC HTR relay malfunction
    • Harness or connector
    		 Refer to PTC Heater Circuit [12/2019 - 11/2023]
    w/ Stop and Start System:
    • No warm air comes out (Blower control is normal)
    • Outlet air temperature does not increase (Blower control is normal)
    • Temperature of outlet air is warmer on left or right side (When same temperature set for both sides)
    1. A/C W/PMP relay (Air conditioning water pump relay) malfunction
    2. Heater water pump assembly malfunction
    3. Air conditioning amplifier assembly malfunction
    4. Engine stop and start ECU malfunction
    		 Refer to Heater Water Pump Circuit [12/2019 - ]
  5. BLOWER CONTROL 
    Symptom Suspected Area Link
    No air flows from the registers
    • Air conditioning amplifier assembly malfunction
    • Blower motor with fan sub-assembly malfunction
    • Rear blower motor with fan sub-assembly malfunction
    • Warm-up control
    • Engine coolant temperature sensor malfunction
    • Harness or connector
    		 Refer to Blower Motor does not Operate [12/2019 - ]
    Airflow volume cannot be changed
    • Air conditioning amplifier assembly malfunction
    • Blower motor with fan sub-assembly malfunction
    • Rear blower motor with fan sub-assembly malfunction
    • Harness or connector
    • Airflow volume is constantly low
    • Airflow volume sometimes becomes low
    		 for Front air conditioning unit: 
    • ECO mode control of air conditioning system is enabled
    • Blower motor with fan sub-assembly malfunction
    • Clogged clean air filter
    • Clogged No. 1 cooler evaporator sub-assembly or heater radiator unit sub-assembly fins
    • Evaporator temp. sensor (No. 1 cooler thermistor)
    • Aspirator pipe not connected properly

    for Rear air conditioning unit: 

    • ECO mode control of air conditioning system is enabled
    • Rear blower motor with fan sub-assembly malfunction
    • Clogged rear evaporator sub-assembly
    		 Refer to Weak Blower Output [12/2019 - 10/2022]
  6. AIR INLET CONTROL 
    Symptom Suspected Area Link
    • Recirculation/fresh mode changes without permission
    • Recirculation/fresh mode light blinks
    • Customize setting*
    • Change in ambient air temperature
    • Decrease in refrigerant pressure
    • Air conditioner pressure sensor circuit malfunction
    • Engine coolant temperature (high)
    		 Refer to Recirculated/Fresh Air Modes Switch without User Input [12/2019 - 11/2023]
    • Air inlet mode cannot be changed between recirculation/fresh
    • Exhaust gas odors can be smelled when air inlet mode set to recirculation mode
    • No. 1 blower damper servo sub-assembly malfunction
    • Damper link disconnection
    • Air inlet damper mechanically locked
    • Engine coolant temperature (high)
    • Air conditioner unit assembly malfunction
    		 Refer to Recirculated/Fresh Air Modes do not Switch [12/2019 - 11/2023]

    *: except USA and Canada

  7. AIR OUTLET CONTROL 
    Symptom Suspected Area Link
    Air outlet mode cannot be changed
    1. (Air outlet display changes)
    • No. 1 air conditioning radiator damper servo sub-assembly malfunction
    • No. 2 air conditioning radiator damper servo sub-assembly malfunction
    • Rear mode damper servo sub-assembly malfunction
    • Damper link disconnection
    • Air conditioner unit assembly malfunction
    		 Refer to Air Vent cannot be Switched [12/2019 - 10/2022]
    Air outlet mode cannot be changed
    1. (Air outlet display does not change)
    • Air conditioning control assembly
    • No. 2 air conditioning control assembly
  8. DEFROSTER CONTROL 
    Symptom Suspected Area Link
    Windshield frequently fogs up
    • Compressor with pulley assembly malfunction
    • Refrigerant volume (low)
    • Cooler expansion valve (opened excessively)
    • No. 2 air conditioning radiator damper servo sub-assembly malfunction
    • Mechanical locking of damper and damper link
    		 Refer to Front Window Fogging [12/2019 - 11/2023]
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