Automatic Dual Zone
The A/C-heater control (1) for the automatic temperature control (ATC) dual zone heating-A/C system allows both the driver and the front seat passenger the ability to individually regulate air temperature for their side of the vehicle. All controls are identified by ISO graphic symbols.
The ATC A/C-heater control and integral computer is located in the instrument panel and contains:
- a push button A/C on/off control (2). The Snowflake button contains an LED that illuminates when the A/C system is in operation.
- a push button rear window defogger on/off control (3). The defogger button contains an LED that illuminates when the rear window defogger system is in operation.
- an infrared sensor (4) that detects thermal radiation emitted by the front seat occupants and their surroundings
- a push button air recirculation control (5). The Recirculation button contains an LED that illuminates when the recirculation function is manually activated.
- a rotary control knob for mode control of the discharged air (6).
- two rotary control knobs for individual driver and front seat passenger temperature control of the discharged air (7).
- a rotary control knob for manual and automatic fan speed selection and turning the heating-A/C system off (8).
- Auto mode provides variable air recirculation under high temperature and humidity conditions. Because recirculation is generally accompanied by increased fan noise, the proportion of recirculated to outside air gradually approaches full recirculation over a broad temperature range.
The A/C-heater control for the ATC dual zone heating-A/C system is diagnosed using a scan tool. 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 calibration procedure to verify that the concern is not a system issue. Refer to HEATING AND A/C SYSTEMS and to DIAGNOSIS AND TESTING for more information.
The A/C-heater control cannot be repaired and, if faulty or damaged, it must be replaced.
The ATC A/C-heater control utilizes integrated circuitry and information carried on the controller area network (CAN) B bus to monitor many sensors and switch inputs throughout the vehicle. In response to those inputs, the internal circuitry and programming of the ATC A/C-heater control allows it to control electronic functions and features of the ATC heating-A/C system.
Some of the inputs received by the A/C-heater control of the ATC heating-A/C system on the CAN B bus are as follows:
- Controlhead backlight dimming
- Refrigerant Pressure
- A/C Clutch Engage
- Vehicle Identification Number
- Vehicle Odometer
- Engine Coolant Temperature
- Ambient Air Temperature
- System Voltage
- Vehicle Speed
- Engine Speed
Some of the messages broadcasted by the A/C-heater control of the ATC heating-A/C system on the CAN B bus are as follows:
- A/C Request
- A/C Select
- EBL Status