Recirculated/Fresh Air Modes do not Switch [11/2021 - ]: Procedure

WARNING: This page is about a different car, the 2025 Lexus NX 350h, 2024 Lexus NX 350h, 2023 Lexus NX 350h, and 2022 Lexus NX 350h. However, it is still accessible from the selected car via links, so may be relevant.

CHECK NO. 3 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY

Check that the No. 3 air conditioning radiator damper servo sub-assembly is installed correctly.

No. 3 air conditioning radiator damper servo sub-assembly is installed correctly.

Result

Proceed to
OK
NG

Result:

REINSTALL NO. 3 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY. Refer to REASSEMBLY [11/2021 - ]

Result:

See step 2

CHECK FOR DTC

Check for DTCs.

Body Electrical > Air Conditioner > Trouble Codes

Result

Result	Proceed to
B143A-87 and B143B-7F are not output	A
B143A-87 is output	B
B143B-7F is output	C

Result:

GO TO DTC B143A-87. Refer to DTC B143A-87: Lost Communication with Air Inlet Damper Control Servo Motor LIN Missing Message [11/2021 - ]

Result:

GO TO DTC B143B-7F. Refer to DTC B143B-7F: Air Inlet Damper Control Servo Motor Actuator Stuck Off [11/2021 - ]

Result:

See step 3

READ VALUE USING GTS

Read the Data List according to the display on the GTS.

Powertrain > Engine > Data List

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
Coolant Temperature	Engine coolant temperature	Min.: -40°C (-40°F) Max.: 140°C (284°F)	75 to 100°C (167 to 212°F): After warming up	This is the engine coolant temperature. HINT: After warming up the engine, the engine coolant temperature will be 75 to 100°C (167 to 212°F). After a long soak, the engine coolant temperature, intake air temperature and ambient air temperature will be approximately equal. If the value is -40°C (-40°F), or higher than 135°C (275°F), the sensor circuit is open or shorted. Check if the engine overheats if the value indicated is higher than 135°C (275°F).

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Coolant Temperature

Engine coolant temperature

Min.: -40°C (-40°F)
Max.: 140°C (284°F)

75 to 100°C (167 to 212°F): After warming up

This is the engine coolant temperature.

HINT:

After warming up the engine, the engine coolant temperature will be 75 to 100°C (167 to 212°F).
After a long soak, the engine coolant temperature, intake air temperature and ambient air temperature will be approximately equal.
If the value is -40°C (-40°F), or higher than 135°C (275°F), the sensor circuit is open or shorted.
Check if the engine overheats if the value indicated is higher than 135°C (275°F).

Powertrain > Engine > Data List

Tester Display
Coolant Temperature

The value of the display does not change frequently.

Result

Proceed to
OK
NG

Result:

REPLACE AIR CONDITIONER UNIT ASSEMBLY. Refer to REMOVAL [11/2021 - 03/2022] , or refer to REMOVAL [03/2022 - 03/2024] , or refer to REMOVAL [03/2024 - ]

Result:

GO TO COOLING SYSTEM. Refer to ON-VEHICLE INSPECTION [11/2021 - ]