Front - Automatic Dual Zone

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 International Standardization Organization (ISO) graphic symbols.

The ATC A/C-heater control and integral computer is located in the center of the instrument panel and contains:

- a push button A/C on/off control (2). An ISO Snowflake symbol appears in the Vacuum-Fluorescent (VF) digital display (3) when the A/C system is in operation, whether under manual or Auto mode.
- a push button front window defogger control (4). An indicator lamp illuminates in the control when selected manually and an ISO symbol appears in the VF digital display when selected by Auto mode.
- four push button temperature controls (5 and 15) to select the front comfort temperatures from 15° to 31° C (60° to 88° F). Comfort temperatures for each zone are shown in the VF digital display. If the set temperatures are 15° C (60° F) and is adjusted lower, the A/C-heater control will attempt to achieve the lowest temperature possible, but the display will show LO. If the set temperatures are 31° C (88° F) and is adjusted up, the A/C-heater control will attempt to achieve the highest temperature possible, but the display will show HIGH. Temperatures can be displayed in either Metric or Fahrenheit, which is selected from the overhead console.
- a push button rear window defogger on/off control (6). An indicator lamp illuminates in the control when selected. The indicator lamp illuminates in the control even with the heating-A/C system turned off Heated Glass - Operation.
- a push button automatic mode control (7) to set the heating-A/C system to Auto mode. AUTO appears in the VF digital display when the system is in Auto mode.
- two push button front heated seat controls (8 and 11). Each control has two indicator lamps that illuminate, depending on seat temperature selected Heated Seats - Operation.
- a rotary control knob for fan speed selection and turning the heating-A/C system off (9).
- a cab temperature sensor (10) is located in the center of the A/C-heater control. The sensor detects thermal radiation emitted by the front seat occupants and their surroundings.
- a push button mode control (12) to override the Auto mode. An ISO mode symbol appears in the VF digital display to indicate the current mode setting when selected manually or by Auto mode. Auto mode provides variable air recirculation through a broad range of high temperature and humidity conditions.
- a push button air recirculation control (13). The Recirculation button contains an LED that illuminates when the recirculation function is manually activated. The ATC A/C-heater control computer logic provides variable air recirculation through a broad range of temperature and humidity conditions.
- a push button synchronize control (14) that automatically adjusts the temperature of the front passenger comfort zone to the drivers comfort zone temperature. An LED illuminates in the SYNC button when the SYNC function is manually activated. SYNC appears in the VF digital display when the system is synchronized, whether under manual or Auto mode.
- illumination lamps for backlighting of the ATC A/C-heater control.
- computer logic that remembers the settings of the controls when the ignition is turned off, and retains those settings after a restart. If the system is off when the ignition is turned off, it will be off when the engine is restarted, etc.

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 initiate the Actuator Calibration function to verify that the concern is not a heating-A/C system calibration issue .

The A/C-heater control cannot be repaired or adjusted and must be replaced if inoperative or damaged.

The ATC A/C-heater control utilizes integrated circuitry and information carried on the Controller Area Network (CAN) bus to monitor many sensors and switch inputs throughout the vehicle. In response to these inputs, the internal circuitry and programming of the ATC A/C-heater control allow 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 bus are as follows:

- A/C Clutch Engage
- Ambient Air Temperature
- A/C-heater control backlight dimming
- Engine Coolant Temperature
- Engine Speed
- Refrigerant Pressure
- Electrical System Voltage
- Vehicle Identification Number
- Vehicle Odometer
- Vehicle Speed

Some of the messages broadcasted by the A/C-heater control of the ATC heating-A/C system on the CAN bus are as follows:

- A/C Request
- EBL Status
- Heated/Ventilated Seat Select