Automatic Temperature Control (ATC) System
AUTOMATIC TEMPERATURE CONTROL (ATC)
The Automatic Temperature Control (ATC) single zone heating and A/C system maintains the interior comfort level desired by the vehicle operator. This is accomplished by use of two air duct temperature sensors, located in the HVAC housing, that measure the temperature of the conditioned air leaving the HVAC housing and an in-car temperature sensor, located in the A/C heater control, that measures the temperature of the conditioned air within the vehicle. Based on the sensors inputs, the ATC system automatically adjusts the air temperature, airflow volume, airflow distribution and amount of inside air recirculation to maintain occupant comfort, even under changing outside weather conditions. All controls are identified by International Standards Organization (ISO) graphic symbols.
The ATC heating and A/C system uses electrically operated controls. These controls provide the vehicle operator with a number of setting options to help control the climate and comfort within the vehicle and offers several manual override features such as fan speed and airflow distribution. When the outside air contains smoke, odors, high humidity, or if rapid cooling is desired, the interior conditioned air can be recirculated within the vehicle.
The A/C heater control and integral computer (1) is located in the instrument panel and contains:
- a two push buttons for temperature control of the discharged air (2). The control contains a Light Emitting Diode (LED) that displays the selected desired temperature (3).
- a two push buttons for manual blower motor speed selection (5). The control contains an LED that displays the selected blower motor speed (4).
- a push button for manually selecting Floor/Defrost mix mode of the discharged air (6). The control contains an indicator lamp that illuminates when the Floor/Defrost mix is selected.
- a push button for manually selecting front window Defrost mode of the discharged air (7). The control contains an indicator lamp that illuminates when Defrost mode is selected.
- a push button for manually selecting Floor mode of the discharged air (8). The control contains an indicator lamp that illuminates when the Floor mode is selected.
- a push button for manually selecting Panel mode of the discharged air (9). The control contains an indicator lamp that illuminates when the Panel mode is selected.
- a in-car temperature sensor and aspirator motor that measures the temperature of the discharged air within the passenger compartment (10) In-Car Temperature Sensor - Description.
- a push button for turning the heating and A/C system Off (11). The control contains an indicator lamp that illuminates when the heating and A/C system is off.
- a push button for recirculating the conditioned air within the vehicle (12). The control contains an indicator lamp that illuminates when the heating and A/C system is in Recirculation mode.
- a push button for selecting automatic control of the discharged air (13). The control contains an indicator lamp that illuminates when the heating and A/C system is in Auto mode.
- a push button for manually turning the A/C system on and off (14). The control contains an indicator lamp that illuminates when the A/C system is in operation.
- The control panel (15) has a lower accessory switch pod (16) that can contain switches for the heated seat system, electronic stability program and the fog lights, depending on how equipped Instrument Cluster Switch Pod - Description.
The A/C heater control for the ATC heating and A/C system obtains vehicle speed, engine speed, engine coolant temperature and refrigerant system head pressure data over the Controller Area Network (CAN) data bus and is diagnosed using a scan tool A L L Diagnostic Trouble Codes ( DTC ).
Prior to replacing the A/C heater control, check for any Diagnostic Trouble Codes (DTCs) related to the heating and A/C system, and run the Actuator Calibration function using a scan tool to verify that the concern is not an air door calibration issue .
The A/C heater control cannot be adjusted or repaired and must be replaced if inoperative or damaged.