Cabin Temperature Sensor / Switch: Description and Operation
INFRARED TEMPERATURE SENSOR - FRONTFig.20 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 and air conditioning 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 heater-A/C 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 DRB III scan tool. Refer to the appropriate diagnostic information.
INFRARED TEMPERATURE SENSOR - REAR
The rear infrared temperature sensor consists of an infrared transducer that is concealed behind the lens of the rear heater-A/C control in the headliner. This sensor is used only on models equipped with the optional Automatic Temperature Control (ATC) heating and air conditioning system. The rear infrared temperature sensor is integral to the rear heater-A/C control. The infrared sensor cannot be adjusted or repaired and, if faulty or damaged, the rear heater-A/C control unit must be replaced.
The rear infrared temperature sensor provides an independent measurement input to the Automatic Temperature Control (ATC) heater-A/C control module that indicates the surface temperature of the rear 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 input by calculating and adjusting the air flow temperature and air flow rate needed to properly obtain and maintain the selected comfort level temperatures for the rear seat occupants. The ATC heater-A/C control module continually monitors the infrared sensor circuit, 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 DRB III scan tool. Refer to the appropriate diagnostic information.