Automatic Temperature Control (ATC)
DESCRIPTION
The ATC Heating, Ventilation and Air Conditioning (HVAC) system is comprised of the following three subsystems, refer to the following for more information:
- Refer to PLUMBING, DESCRIPTION AND OPERATION (Orange)
- Refer to DISTRIBUTION, DESCRIPTION AND OPERATION (Light Blue)
- Refer to CONTROLS, DESCRIPTION AND OPERATION (Red)
OPERATION
With the automatic system, the operator can choose either automatic or manual operation. During automatic operation, the operator simply sets a target temperature. The Air Conditioning (A/C) and heater module, called the HVAC module, determines the best combination of A/C compressor operation, blend door position, outlet air direction and speed to control passenger compartment humidity and reach the target temperature. During manual operation, the operator can select A/C operation, air flow speed, air flow outlet location, and choose either fresh or recirculated air.
The HVAC module is connected to the Controller Area Network - Interior High Speed (CAN-IHS) data bus and receives the information of the humidity sensor from the Instrument Panel Cluster (IPC) and ambient temperature via CAN. The system manages air recirculation, distribution and temperature using the actuators with potentiometer, for opening, closing and regulating the intermediate positions via electrical commands. The HVAC module controls the mixing temperatures through the temperature sensors located in the HVAC housing. The system manages the air temperature request by also monitoring solar radiation through a dedicated sensor located on the steering column opening cover. The A/C activation request from the user and the heated rear window activation request is sent to and activated by the Body Control Module (BCM) via CAN. The A/C request status and the actuator position are stored in the HVAC module. The HVAC also manages activation of the rear window defroster.
To maintain the performance level of the HVAC system, the engine cooling system must be properly maintained. The use of a bug screen is not recommended. Any obstructions in front of the radiator or A/C condenser will reduce the performance of the A/C and engine cooling systems. The engine cooling system includes the radiator, thermostat, radiator hoses and the engine coolant pump. (Refer to 3.0L, COOLING SYSTEM, DESCRIPTION AND OPERATION or 3.6L, COOLING SYSTEM, DESCRIPTION AND OPERATION ) for more information before opening or attempting any service to the engine cooling system.