Air Temperature Sensor ( Ambient / Intake ): Description and Operation
AIR TEMPERATURE SENSORSThe air temperature sensor is a 2 wire negative temperature co-efficient thermistor. The vehicle uses the following air temperature sensors:
- Ambient
- Inside
A signal and low reference circuit enables the sensor to operate. As the air temperature surrounding the sensor increases, the sensor resistance decreases. The sensor signal decreases as the resistance decreases. The sensor signal varies between 0-5 volts. The HVAC control module converts the signal to a range between 0-255 counts.
The HVAC control module uses the sensor signals to determine the air temperature door position. The air temperature sensor inputs in a dual zone HVAC system are used to adjust the corresponding left and right air temperature door.
If the HVAC control module detects a malfunctioning sensor, then the HVAC control module will set a DTC code. The HVAC control module will substitute a temperature value of 24°C (75°F) if the inside air temperature sensor has a failure. If the ambient air temperature sensor fails, a temperature of 9°C (49°F) will be substituted by the HVAC control module. The default action ensures that the HVAC system can adjust the inside air temperature near the desired temperature until the condition is corrected.
The HVAC control module displays the ambient air temperature value. The ambient air temperature value is displayed or updated under the following conditions: