Normal Operation and Fault Conditions
The evaporator temperature sensor receives a ground from the HVAC module. The sensor varies its resistance with the temperature. As the temperature rises, the resistance falls. As the temperature falls, the resistance rises. The HVAC module measures this resistance to determine the temperature at the sensor.
The evaporator temperature sensor is used for A/C compressor cycling. An accurate evaporator temperature is critical to prevent evaporator icing. The HVAC module uses the temperature measurement to turn off the A/C compressor before the evaporator temperatures are cold enough to freeze the condensation. This prevents ice blockage of airflow over the evaporator core.
DTC FAULT TRIGGER CONDITIONS
| DTC | Description | Fault Trigger Conditions |
|---|---|---|
| B1B71:11 | Evaporator Temperature Sensor: Circuit Short to Ground | This CMDTC sets when the HVAC module senses lower than expected voltage on the evaporator temperature sensor feedback circuit. |
| B1B71:15 | Evaporator Temperature Sensor: Circuit Short to Battery or Open | This CMDTC sets when the HVAC module senses greater than expected voltage on the evaporator temperature sensor feedback circuit, indicating a short to voltage or an open circuit or sensor. |