Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Problem Symptoms Table
PROBLEM SYMPTOMS TABLE
NOTICE:
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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.
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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)".
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Before replacing the ECM, refer to Registration.
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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.
| 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
| 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 ...
Other materials:
Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual > Occupant Classification System: Initialization
INITIALIZATION DESCRIPTION (a) Zero point of the occupant classification sensors may deviate in the following situations. To ensure sensor accuracy, be sure to perform Zero Point Calibration.
The occupant detection ECU is replaced. HINT: As the zero point is not automatically stored in a new occu ...
Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual > Navigation System: Speed Signal Malfunction (B15C2)
DESCRIPTION The navigation ECU receives a vehicle speed signal from the combination meter assembly and information from the navigation antenna assembly, and then adjusts the vehicle position on the map. The navigation ECU stores this DTC when the difference between the speed information that the nav ...
Lexus RX (RX 350L, RX450h) 2016-{YEAR} Owners Manual
- For your information
- Pictorial index
- For safety and security
- Instrument cluster
- Operation of each component
- Driving
- Lexus Display Audio system
- Interior features
- Maintenance and care
- When trouble arises
- Vehicle specifications
- For owners
Lexus RX (RX 350L, RX450h) 2016-{YEAR} Repair Manual
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