Part 2
Control Components
Air Temperature Control - Single Zone Manual System
Cabin temperature selection is made by turning the LH rotary controller to the required position. Turning the controller counter clockwise will lower the temperature of the air exiting the heater assembly; turning the controller clockwise will raise the temperature of the air exiting the heater assembly.
Maximum heating and cooling is represented on the control panel by a red and blue dot respectively. When either maximum heating or cooling is selected, the 'comfort' algorithm in the ATC module will adopt a suitable strategy for air source, air distribution and blower speed to maintain maximum heating or cooling within the cabin.
The ATC module adjusts the temperature of the air exiting the heater assembly by moving the position of the temperature blend door. The temperature blend door directs a proportion of cooled air from the evaporator through the heater core to produce the required temperature output. The ATC module adjusts the position of the temperature blend door by providing LIN bus messages to the blend door stepper motor. A Hall effect sensor located within the stepper motor informs the ATC module that movement of the stepper motor is taking place.
Air Temperature Control - Dual Zone Automatic System
Dual zone systems feature 2 rotary heating controllers, which allow individual climate control for the LH and RH sides of the cabin. Temperature selection can be made by turning the controller to the required temperature marked on the control panel. Turning either controller past the 16°C (61°F) mark will initiate the maximum cooling strategy; turning either controller past the 28°C (82°F) mark will initiate the maximum heating strategy.
NOTE:
Maximum cooling or heating can only be achieved if both rotary controllers are set to the same position.
The ATC module is able to maintain constant temperatures in both sides of the cabin by monitoring the feedback from the cabin temperature sensor. Unless any manual overrides have been selected, the ATC module will automatically control the intake air source, air distribution into the cabin and blower speed to maintain the required temperatures.
Dual zone systems feature 2 temperature blend doors, allowing individual temperature output for the LH and RH sides of the cabin.
NOTE:
The drivers side temperature setting has priority over the passengers side temperature setting.
The temperature blend doors are mounted on the LH side of the heater assembly and direct a proportion of cooled air from the evaporator through the heater core to provide the required temperature outputs. The ATC module controls the position of the temperature blend doors by providing LIN bus messages to the blend door stepper motors. Hall effect sensors located within the stepper motors inform the ATC module that movement of the stepper motors is taking place.
Blower Motor Control - Single Zone Manual System
Blower motor speed is set by turning the RH rotary controller to the required position. The RH rotary controller allows the selection of 14 blower motor speeds. Turning the controller fully counter clockwise will turn the blower motor off.
Operation of the blower motor is controlled by the ATC module via the blower motor control module. The ATC module provides a PWM signal to the blower motor control module based on the selected blower speed. The blower motor control module interprets the PWM signal as a blower motor speed and controls the voltage to the blower motor accordingly.
Blower Motor Control - Dual Zone Automatic System
Blower motor speed is controlled automatically by the ATC module unless a manual override has been requested. Manual overrides to blower motor speed can be made by turning the central rotary controller to the required position. The rotary controller allows the manual selection of 7 blower motor speeds. Turning the controller fully counter clockwise will turn the blower motor off. When a manual override has been made, the 'AUTO' LED located in the center of the rotary controller will extinguish.
NOTE:
The central rotary controller contains 2 LED's. The top (round) LED will illuminate when the blower motor is under automatic control. The bottom (rectangular) LED will illuminated when air distribution into the cabin is under automatic control (see below).
The blower motor can be returned to automatic control by pressing the 'AUTO' switch located in the center of the rotary controller. Under automatic control, the ATC module varies the speed of the blower motor in line with its 'comfort' algorithm to maintain the required cabin temperature. The ATC module will also vary the blower motor speed to compensate for the ram effect on intake air produced by forward movement of the vehicle.
Operation of the blower motor is controlled by the ATC module via the blower motor control module. The ATC module provides a PWM signal to the blower motor control module based on the required blower speed. The blower motor control module interprets the PWM signal as a blower motor speed and controls the voltage to the blower motor accordingly.
Air Distribution Control - Single Zone Manual System
Air distribution into the cabin can be adjusted by turning the central rotary controller to the required position. The ATC module adjusts the position of the air distribution door to the required position by providing LIN bus messages to the air distribution door stepper motor. A Hall effect sensor located within the stepper motor informs the ATC module that movement of the stepper motor is taking place.
Air Distribution Control - Dual Zone Automatic System
Air distribution into the cabin is controlled automatically by the ATC module unless any manual overrides have been requested. Manual overrides can be made by pressing the appropriate air distribution momentary switch on the control panel. If a manual override has been requested, the 'AUTO' LED located in the center of the blower motor rotary controller will extinguish.
NOTE:
The central rotary controller contains 2 LED's. The top (round) LED will illuminate when the blower motor is under automatic control (see above). The bottom (rectangular) LED will illuminated when air distribution into the cabin is under automatic control.
Air distribution can be returned to automatic control by pressing the 'AUTO' switch located in the center of the blower motor rotary controller. This will illuminate the 'AUTO' LED and allow the ATC module to control air distribution in line with its 'comfort' algorithm
Air distribution is controlled by 2 air distribution doors. The ATC module controls the position of the air distribution doors by providing LIN bus messages to the door stepper motors. Hall effect sensors located within the stepper motors inform the ATC module that movement of the stepper motors is taking place.
ECON - Single Zone Manual System
Pressing the 'ECON' momentary switch on the control panel will switch off the A/C system. When selected, the ATC module will transmit a message over the high speed CAN bus to the ECM requesting the A/C compressor is disabled. The ECM disables the compressor by de-energizing the A/C compressor control relay located in the BJB. The tell-tale LED in the switch will illuminate to alert the vehicle occupants that the system is in 'ECON' mode.
When 'ECON' mode is selected, temperature control is still available but no cooling of intake air will take place. The minimum output air temperature from the system will be ambient air temperature plus any heat pick up in the air intake path.
A/C can be switched back on by pressing the 'ECON' switch a second time. This will also extinguish the 'ECON' LED.
Stop/Start Vehicles - From 2010 MY
From 2010 MY, the 'ECON' switch will be labeled 'A/C' to prevent confusion with the 'Eco' switch which operates the 'Stop/Start' and 'Gear Change Indicator' systems. For additional information, refer to Starting System
ECON - Dual Zone Automatic System
Pressing the 'ECON/OFF' momentary switch in the control panel will switch off the A/C system. When selected, the ATC module will transmit a message over the high speed CAN bus to the ECM requesting the A/C compressor is disabled. The ECM disables the compressor by de-energizing the A/C compressor control relay located in the BJB. The 'ECON' tell-tale LED in the switch will illuminate to alert the vehicle occupants that the system is in 'ECON' mode.
When 'ECON' mode is selected, temperature control is still available but no cooling of intake air will take place. The minimum output air temperature from the system will be ambient air temperature plus any heat pick up in the air intake path.
A second press of the 'ECON/OFF' switch will extinguish the 'ECON' LED and illuminate the 'OFF' LED. When in 'OFF' mode the ATC module sets the blower motor speed to 0. Air distribution into the cabin will remain as previously selected. All LED's on the control panel will be extinguished, although night time illumination will remain active.
NOTE:
When in 'OFF' mode, the heated seat, heated windshield and heated rear window functions will still be available.
A third press of the 'ECON/OFF' switch returns the system to normal (A/C) operation and extinguishes the 'OFF' LED. The system can be returned to automatic operation at any time by pressing the 'AUTO' switch mounted in the central (blower motor) rotary controller.
Stop/Start Vehicles - From 2010 MY
From 2010 MY, the 'ECON' switch will be labeled 'A/C' to prevent confusion with the 'Eco' switch which operates the 'Stop/Start' and 'Gear Change Indicator' systems. For additional information, refer to Starting System
Programmed Defrost
The programmed defrost function is only available on vehicles fitted with a dual zone heating, ventilation and A/C system. The function is selected by pressing the 'PROG' momentary switch on the control panel. When selected, the ATC module provides maximum windshield defrosting/demisting by configuring the system as follows:
- 'AUTO' mode off
- Intake air set to fresh air
- Air distribution set to windshield
- Blower motor speed set to maximum
- Heated windshield on
- Rear window heater on.
When programmed defrost is selected, the set temperature will remain unchanged. Programmed defrost can be cancelled by any of the following methods:
- Pressing any air distribution momentary switch
- Pressing the 'AUTO' switch located in the center of the blower motor rotary controller
- Pressing the 'PROG' momentary switch a second time.
NOTE:
Blower motor speed can be adjusted without terminating programmed defrost.
Windshield Heater
The windshield heater comprises 2 heater elements, LH and RH, bonded between the glass laminations. The system is switched on by pressing the momentary switch located on the control panel. When selected, the ATC module transmits a heating request on the high speed CAN bus to the CJB. On receipt of the message, the CJB energizes the windshield heater relay located in the BJB by providing a ground path for the relay coil. The energized relay provides a battery feed to both heater elements. After a period of 4 minutes the ATC module removes the request for windshield heating. The CJB then powers down the windshield heater by removing the ground path for the relay coil.
The ATC module will only request windshield heater operation if the engine is running. An engine status signal is provided to the ATC module by the ECM over the high speed CAN bus.
Rear Window Heater
The rear window heater comprises a single heater element bonded to the inner surface of the glass. The system is switched on by pressing the momentary switch located on the control panel. When selected, the ATC module transmits a heating request on the high speed CAN bus to the CJB. On receipt of the message, the CJB energizes the rear window heater relay located in the Auxiliary Junction Box (AJB) by providing a ground path for the relay coil. The energized relay provides a battery feed to the heater element. After a period of 12 minutes the ATC module removes the heating request. The CJB then powers down the rear window heater by removing the ground path for the relay coil.
The ATC module will only request rear window heater operation if the engine is running. An engine status signal is provided to the ATC module by the ECM over the high speed CAN bus.
Exterior Mirror Heaters
Operation of the exterior mirror heaters is fully automatic and requires no input from the driver. The exterior mirror heaters are active when the ambient air temperature is below 5°C (41°F) and engine coolant temperature is below 65°C (149°F). Ambient air and engine coolant temperature values are provided by the ECM on the high speed CAN bus. On receipt of these temperature values, the CJB determines if exterior mirror heating is required.
The CJB requests exterior mirror heating by transmitting a high speed CAN bus message to both the drivers and passenger door modules. The door modules provide feed and ground paths to the respective exterior mirror heating elements. When ambient and engine coolant temperature rises above the values stated earlier, the CJB transmits a high speed CAN bus message to the door modules canceling the heating request.
Seat Heaters
Operation of the seat heaters is controlled by the ATC module on receipt of a heating request from either of the seat heater momentary switches located on the control panel. The switches are mounted in the LH and RH rotary controllers. A single press of a seat heater switch will implement low level heating and illuminate a tell-tale LED. A second press of the switch will implement high level heating and illuminate 2 tell-tale LED's. A third press of the switch will turn the seat heater off.
Seat heating requests are transmitted from the ATC module to the seat heater control modules on the LIN bus. Two seat heater control modules are fitted, one under each front seat. The seat heater control modules provide an electrical supply to the seat heater elements and a temperature sensor located in the seat cushion.
The seat heater control module provides a 5 V reference feed to the seat heater temperature sensor. The seat heater temperature sensor is an NTC thermistor. By monitoring the returned voltage, the control module can calculate the temperature of the seat. If the temperature rises above the target temperature, the control module will disable operation of the heater elements.