Grand Caravan V6-3.3L VIN R (2005)
Ambient Temperature Sensor / Switch HVAC: Description and Operation
Infrared Temperature Sensor
Infrared Temperature Sensor - RS Shown, RG Typical
The infrared temperature sensor consists of two infrared transducers that are concealed behind a clear lens located 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.
The infrared sensor detects thermal radiation emitted by the driver and front passenger seat occupants and their surroundings and converts its data into a
linear pulse width modulated (PWM) output signal which is read by the automatic temperature control (ATC) A/C-heater control. The ATC A/C-heater
control uses the infrared sensor data as one of the inputs necessary to automatically control the interior cabin temperature level. By using thermal
radiation (surface temperature) measurement, rather than an air temperature measurement, the ATC heating-A/C system is able to adjust itself to the
comfort level as perceived by the occupant. This allows the ATC system to 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 message by calculating and adjusting the air flow temperature and air flow rate needed to properly
obtain and maintain the selected comfort level temperature of the occupants. The A/C-heater control continually monitors the infrared sensor circuits,
and will store diagnostic trouble codes (DTCs) for any problem it detects.
The infrared sensor is diagnosed using a DRBIII(R) scan tool.
The infrared sensor cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
