Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual: Problem Symptoms Table

PROBLEM SYMPTOMS TABLE

NOTICE:

  • If the battery voltage is low, the PTC heater may not operate. When "Operation of Electrical Items Restricted." is displayed on the multi-information display in the combination meter assembly, inspect the battery, referring to On-vehicle Inspection for the charging system.

    Click here

  • If the battery voltage is low, the PTC heater may not operate. When "Operation of Electrical Items Restricted." is not displayed on the multi-information display in the combination meter assembly, check the Data List item "Battery Control Count (Body ECU)".

    Click here

  • Before replacing the ECM, refer to Registration.

    Click here

HINT:

  • 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.
Front Air Conditioning System

Symptom

Suspected Area

Link

All functions of the air conditioning system do not operate

IG power source circuit

Back-up power source circuit

Air conditioning control panel circuit

Air conditioning amplifier assembly

Air flow Control: No blower operation

Blower motor circuit

Air conditioning control panel circuit

Air conditioning amplifier assembly

Air flow control: No blower control

Blower motor circuit

Air conditioning control panel circuit

Air conditioning amplifier assembly

Air flow control: Insufficient air flow

Blower motor circuit

Air conditioning amplifier assembly

Temperature control: Cooling effectiveness is poor

Refrigerant shortage check using the Techstream

Refrigerant volume

-

Refrigerant pressure

Cooler expansion valve

Cooler compressor assembly

Air conditioning amplifier assembly

Temperature control: No cool air comes out

Refrigerant shortage check using the Techstream

Refrigerant volume

-

Refrigerant pressure

Air conditioner pressure sensor circuit

Air conditioning control panel circuit

Air mix damper control servo motor circuit (for driver side)

Air mix damper control servo motor circuit (for front passenger side)

Evaporator temperature sensor circuit

Room temperature sensor circuit

Ambient temperature sensor circuit

Cooler expansion valve

No. 1 air conditioning radiator damper servo sub-assembly (Driver side air mix)

No. 1 air conditioning radiator damper servo sub-assembly (Front passenger side air mix)

Air conditioning harness assembly

Cooler compressor assembly

Air conditioning amplifier assembly

ECM

Temperature control: No warm air comes out

Air conditioning control panel circuit

Air mix damper control servo motor circuit (for driver side)

Air mix damper control servo motor circuit (for front passenger side)

Evaporator temperature sensor circuit

Room temperature sensor circuit

Ambient temperature sensor circuit

PTC heater circuit*1

No. 1 air conditioning radiator damper servo sub-assembly (Driver side air mix)

No. 1 air conditioning radiator damper servo sub-assembly (Front passenger side air mix)

Air conditioning harness assembly

Air conditioning amplifier assembly

ECM

Temperature control: Output air is warmer or cooler than the set temperature or response is slow

Refrigerant shortage check using the Techstream

Refrigerant volume

-

Refrigerant pressure

Compressor solenoid circuit

Room temperature sensor circuit

Ambient temperature sensor circuit

Air conditioning control panel circuit

Air mix damper control servo motor circuit (for driver side)

Air mix damper control servo motor circuit (for front passenger side)

Air inlet damper control servo motor circuit

PTC heater circuit*1

Heater radiator unit sub-assembly

Cooler expansion valve

Automatic light control sensor

No. 1 air conditioning radiator damper servo sub-assembly (Driver side air mix)

No. 1 air conditioning radiator damper servo sub-assembly (Front passenger side air mix)

No. 1 blower damper servo sub-assembly

Air conditioning harness assembly

Air conditioning amplifier assembly

ECM

Temperature control: No temperature control (only MAX COLD or MAX HOT)

Air conditioning control panel circuit

Air mix damper control servo motor circuit (for driver side)

Air mix damper control servo motor circuit (for front passenger side)

Room temperature sensor circuit

Ambient temperature sensor circuit

Evaporator temperature sensor circuit

Automatic light control sensor

No. 1 air conditioning radiator damper servo sub-assembly (Driver side air mix)

No. 1 air conditioning radiator damper servo sub-assembly (Front passenger side air mix)

Air conditioning harness assembly

Air conditioning amplifier assembly

Temperature control: Output air temperature is different between left and right registers (the set temperature is the same for both)

Refrigerant shortage check using the Techstream

Refrigerant volume

-

Refrigerant pressure

Air mix damper control servo motor circuit (for driver side)

Air mix damper control servo motor circuit (for front passenger side)

Automatic light control sensor

No. 1 air conditioning radiator damper servo sub-assembly (Driver side air mix)

No. 1 air conditioning radiator damper servo sub-assembly (Front passenger side air mix)

Air conditioning harness assembly

Air conditioning amplifier assembly

No air inlet control

Air conditioning control panel circuit

Air inlet damper control servo motor circuit

No. 1 blower damper servo sub-assembly

Air conditioning harness assembly

Air conditioning amplifier assembly

No air flow mode control

Air conditioning control panel circuit

Air outlet damper control servo motor circuit (for driver side)

Air outlet damper control servo motor circuit (for front passenger side)

No. 3 air conditioning radiator damper servo sub-assembly (Driver side mode)

No. 1 air conditioning radiator damper servo sub-assembly (Front passenger side mode)

Air conditioning harness assembly

Air conditioning amplifier assembly

Auto recirculation control function does not operate normally*2

Smog ventilation sensor circuit (for HC, CO)

Smog ventilation sensor circuit (for NOx)

Room temperature sensor circuit

Ambient temperature sensor circuit

Air inlet damper control servo motor circuit

Air conditioning control panel circuit

No. 1 blower damper servo sub-assembly

Air conditioning harness assembly

Radio receiver assembly (A/C control panel)

Air conditioning amplifier assembly

Quick heater assembly does not operate*1

PTC heater circuit

Air conditioning amplifier assembly

Combination switch assembly (ECO mode switch) does not operate normally

ECO switch circuit

Air conditioning amplifier assembly

Diagnostic trouble codes (DTCs) are not recorded. Set mode is cleared when the engine switch is turned off

Back-up power source circuit

Air conditioning amplifier assembly

  • *1: w/ PTC Heater
  • *2: w/ Smog Ventilation Sensor
Rear Air Conditioning System (w/ Rear Air Conditioning System)

Symptom

Suspected Area

Link

All functions of the rear air conditioning system do not operate

IG power source circuit

Back-up power source circuit

No. 2 air conditioning control assembly circuit

Air conditioning amplifier assembly

Air flow control: No blower operation

Rear blower motor circuit

No. 2 air conditioning control assembly circuit

Air conditioning amplifier assembly

Air flow control: No blower control

Rear blower motor circuit

No. 2 air conditioning control assembly circuit

Air conditioning amplifier assembly

Air flow control: Insufficient air flow

Rear blower motor circuit

Air conditioning amplifier assembly

Temperature control: No cool air comes out

Refrigerant shortage check using the Techstream

Refrigerant volume

-

Refrigerant pressure

Air conditioner pressure sensor circuit

No. 2 air conditioning control assembly circuit

Rear No. 2 cooling unit damper servo sub-assembly circuit

Rear evaporator temperature sensor circuit

Cooler (No. 2 room temp. sensor) thermistor circuit

Ambient temperature sensor circuit

Rear cooling unit expansion valve

Rear No. 2 cooling unit damper servo sub-assembly

No. 2 air conditioning harness assembly

Cooler compressor assembly

Air conditioning amplifier assembly

ECM

Temperature control: No warm air comes out

No. 2 air conditioning control assembly circuit

Rear No. 2 cooling unit damper servo sub-assembly circuit

Rear evaporator temperature sensor circuit

Cooler (No. 2 room temp. sensor) thermistor circuit

Ambient temperature sensor circuit

Rear No. 2 cooling unit damper servo sub-assembly

No. 2 air conditioning harness assembly

Air conditioning amplifier assembly

ECM

Temperature control: Output air is warmer or cooler than the set temperature or response is slow

Refrigerant shortage check using the Techstream

Refrigerant volume

-

Refrigerant pressure

Automatic light control sensor

Cooler (No. 2 room temp. sensor) thermistor circuit

Rear evaporator temperature sensor circuit

Ambient temperature sensor circuit

No. 2 air conditioning control assembly circuit

Rear No. 2 cooling unit damper servo sub-assembly circuit

Rear air conditioning unit assembly

Rear cooling unit expansion valve

Rear No. 2 cooling unit damper servo sub-assembly

No. 2 air conditioning harness assembly

Air conditioning amplifier assembly

ECM

Temperature control: No temperature control (only MAX COLD or MAX HOT)

No. 2 air conditioning control assembly circuit

Rear No. 2 cooling unit damper servo sub-assembly circuit

Rear evaporator temperature sensor circuit

Ambient temperature sensor circuit

Automatic light control sensor

Rear No. 2 cooling unit damper servo sub-assembly

No. 2 air conditioning harness assembly

Air conditioning amplifier assembly

No air flow mode control

No. 2 air conditioning control assembly circuit

Rear No. 1 cooling unit damper servo sub-assembly circuit

No. 2 air conditioning harness assembly

Air conditioning amplifier assembly

Diagnostic Trouble Codes (DTCs) are not recorded. Set mode is cleared when the engine switch is turned off

Back-up power source circuit

Air conditioning amplifier assembly

    Initialization
    INITIALIZATION INITIALIZATION SERVO MOTOR (a) Turn the engine switch off. (b) Connect the Techstream to the DLC3. (c) Turn the engine switch on (IG). (d) Press the A/C OFF switch. (e) Turn the Techstr ...

    Diagnosis System
    DIAGNOSIS SYSTEM DESCRIPTION Air conditioning system data and Diagnostic Trouble Codes (DTCs) can be read through the Data Link Connector 3 (DLC3) of the vehicle. When the system seems to be malfuncti ...

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    Lexus RX (RX 350L, RX450h) 2016-{YEAR} Owners Manual

    Lexus RX (RX 350L, RX450h) 2016-{YEAR} Repair Manual

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