The P0535 code on your 2021 Lexus ES indicates a malfunction in the A/C evaporator temperature sensor circuit. This sensor monitors evaporator temperature to prevent freezing and optimize cooling.
Evaporator Temperature Sensor Function
The evaporator temperature sensor (also called evaporator thermistor or icing sensor) monitors the temperature of the evaporator core. If the evaporator gets too cold, ice forms and blocks airflow. The ECM cycles the compressor to prevent this.
ES Climate Control
The 2021 Lexus ES features automatic climate control that requires accurate evaporator temperature data. The sensor is located in or near the HVAC evaporator housing inside the dashboard area.
Sensor Malfunction Causes
The thermistor may have failed electrically. Wiring damage affects signal transmission. Connector corrosion from moisture in the HVAC system. The sensor may have physically broken or disconnected. HVAC housing damage during service may have affected the sensor.
Diagnostic Steps
Use Lexus Techstream to monitor evaporator temperature readings. Values should be realistic—typically 35-45°F when A/C is running. Check sensor resistance at different temperatures if accessible. Verify wiring continuity from sensor to ECM. Inspect HVAC connections if dashboard work was recently performed.