Ambient Temperature Sensor / Switch HVAC: Description and Operation

Infrared Temperature Sensor:

INFRARED TEMPERATURE SENSOR
The infrared temperature sensor consists of two infrared transducers that are concealed behind a clear lens located near the bottom of the center panel outlet near the top of the instrument panel center bezel. These sensors are used only on models equipped with the optional automatic temperature control (ATC) heating-A/C system. A molded plastic connector receptacle on the bottom of the panel outlet unit is concealed behind the center bezel. A short, dedicated jumper wire harness routed behind the center bezel connects the sensors directly to the ATC A/C-heater control module near the bottom of the center bezel. The infrared temperature sensor is integral to the center bezel panel outlet unit. The infrared sensors cannot be adjusted or repaired and, if faulty or damaged, the center bezel panel outlet unit must be replaced.

The dual infrared temperature sensors provide independent measurement inputs to the Automatic Temperature Control (ATC) heater-A/C control module that indicates the surface temperature of the driver seat and front seat passenger seat occupants. By using a surface temperature measurement, rather than an air temperature measurement, the ATC system is able to adjust itself to the comfort level as perceived by the occupant. This allows the system to detect and compensate for other ambient conditions affecting comfort levels, such as solar heat gain or evaporative heat loss. The ATC system logic responds to the infrared sensor inputs by calculating and adjusting the air flow temperature and air flow rate needed to properly obtain and maintain the individually selected comfort level temperatures of both the driver and passenger seat occupants. The ATC heater-A/C control module continually monitors the infrared sensor circuits, and will store a Diagnostic Trouble Code (DTC) for any problem it detects. This DTC information can be retrieved and the infrared temperature sensor diagnosed using a DRBIII(R) scan tool. Refer to Body Diagnostic Procedures.