The A/C evaporator temperature sensor is a safety device. It monitors the temperature of the cooling fins on the evaporator core under the dashboard. If the temperature drops close to freezing, the sensor sends a signal to the climate control module. The computer then disengages the A/C compressor clutch. This cycle prevents condensation on the evaporator from turning to ice, which would block airflow into the cabin.
Mechanic Glossary
A C Evaporator Temperature Sensor
A thermistor that monitors the temperature of the A/C evaporator core to prevent it from freezing.
Frequently Asked Questions
The A/C system may shut down completely. Or the compressor will run constantly, causing the evaporator to freeze over, which blocks airflow.
It is inserted directly into the fins of the evaporator core, located inside the HVAC housing under the dashboard.
Use a multimeter to measure the sensor's resistance. Resistance should change predictably as you expose the sensor tip to different temperatures.