Automatic Temperature Control (ATC) System
The A/C-heater control for the automatic temperature control (ATC) single zone system maintains the interior comfort level desired by the vehicle operator. This is accomplished by use of and infrared sensor located in the front overhead console that measures the surface temperature of the driver and front seat passengers. Based on the sensors input, the 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 ISO graphic symbols.
This ATC system offers several manual override features such as fan speed, airflow distribution and 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 heating-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.
The A/C-heater control and integral computer (1) is located in the instrument panel and contains:
- a rotary control for manual and automatic blower motor speed selection and for turning the heating-A/C system on and off (2). This control also contains a push button function for recirculating the conditioned air. The control contains an indicator lamp that illuminates when the heating-A/C system is in recirculation mode.
- a rotary control for temperature control of the discharged air (3). This control also contains a push button function for manually turning the A/C system on and off. The control contains an indicator lamp that illuminates when the A/C system is in operation.
- a rotary control for manual and automatic mode control of the discharged air (4). This control also contains a push button function for turning the rear window defogger system on and off. The control contains an indicator lamp that illuminates when the rear window defogger system is in operation.
The A/C-heater control for the ATC heating and A/C system obtains vehicle speed, engine speed, engine coolant temperature, ambient temperature and refrigerant system head pressure data from the CAN-IHS bus and is diagnosed using a scan tool. Refer to DTC-Based Diagnostics/HVAC - Diagnosis and Testing .
Prior to replacing an A/C-heater control, check for any diagnostic trouble codes (DTCs) related to the heating-A/C system and run the Actuator Calibration function using a scan tool to verify that the concern is not a system issue. Refer to DTC-Based Diagnostics/HVAC - Standard Procedure .
The A/C-heater control cannot be adjusted or repaired and must be replaced if inoperative or damaged.