Part 1
Control Components
NOTE:
A = Hardwired; D = High Speed CAN (controller area network) bus; N = Medium Speed CAN (controller area network) bus; O = LIN (local interconnect network) bus
DW12C is shown, GTDi is similar
Intake Air Control - Dual Zone Automatic System
The intake air source is controlled automatically unless overridden by pressing the fresh/re-circulated air switch located on the control panel. Under automatic control, the ATC (automatic temperature control) module determines the required position of the air intake door using its 'comfort' algorithm based on inputs from the ambient air temperature sensor and the cabin temperature sensor.
When the vehicle first enters power mode 6 (ignition on), the tell-tale LED (light emitting diode) on the fresh/re-circulated air switch will be illuminated and the air intake source will be automatically controlled by the ATC (automatic temperature control) module. The ATC (automatic temperature control) module will control the intake air source according to ambient air temperature and requested cabin temperature. The intake air door will be opened to allow fresh air into the cabin, although a small amount of re-circulated air will also be present.
NOTE:
The ATC (automatic temperature control) module will reduce the amount of fresh air entering the cabin to reduce the ram effect caused by forward motion of the vehicle.
A single press of the fresh/re-circulated air switch will illuminate the tell-tale 'MAN' LED (light emitting diode). The ATC (automatic temperature control) module will now close the air intake door and provide only re-circulated air into the cabin for a period of 3 minutes. After this period, the ATC (automatic temperature control) module will return the air intake door to automatic control. This helps prevent misting within the cabin.
A second press of the fresh/re-circulated air switch will also return the intake air source to automatic control and illuminate the tell-tale 'AUTO' LED (light emitting diode).
The 3 minute time period for re-circulated air can be overridden by pressing and holding the fresh/re-circulated air switch until the switch LED (light emitting diode) flashes 3 times. The air intake door will now remain closed until the next drive cycle.
The ATC (automatic temperature control) module controls the position of the air intake door by providing LIN (local interconnect network) bus messages to the air intake door stepper motor. A Hall effect sensor located within the stepper motor informs the ATC (automatic temperature control) module that movement of the stepper motor is taking place.
Intake Air Control - Dual Zone Automatic System with Pollution Sensor
The intake air source is controlled automatically unless overridden by pressing the fresh/re-circulated air switch located on the control panel. Under automatic control, the ATC (automatic temperature control) module determines the required position of the air intake door using its 'comfort' algorithm based on inputs from the ambient air temperature sensor, the cabin temperature sensor and the pollution sensor.
NOTE:
The ATC (automatic temperature control) module will reduce the amount of fresh air entering the cabin to reduce the ram effect caused by forward motion of the vehicle.
When the vehicle first enters power mode 6 (ignition on), the 'AUTO' tell-tale LED (light emitting diode) on the fresh/re-circulated air switch will be illuminated and the air intake source will be automatically controlled by the ATC (automatic temperature control) module. A single press of the fresh/re-circulated air switch will extinguish the 'AUTO' tell-tale LED (light emitting diode) and illuminate the 'MAN' tell-tale LED (light emitting diode). The ATC (automatic temperature control) module will now close the air intake door and provide only re-circulated air into the cabin for a period of 3 minutes. After this period, the ATC (automatic temperature control) module will return the air intake door to automatic control. This helps prevent misting
within the cabin.
A second press of the fresh/re-circulated air switch will extinguish both the 'AUTO' and 'MAN' tell-tale LED (light emitting diode)'s. The ATC (automatic temperature control) module will now control the intake air source according to ambient air temperature and requested cabin temperature. The air intake door will be opened to allow fresh air into the cabin, but a small amount of re-circulated air will also be present. The amount of re-circulated air is determined by the ATC (automatic temperature control) module using its 'comfort' algorithm based on inputs from the ambient air temperature sensor and the cabin temperature sensor.
A third press of the fresh/re-circulated air switch returns the air intake source to automatic control and will illuminate the 'AUTO' tell-tale LED (light emitting diode).
The 3 minute time period for re-circulated air can be overridden by pressing and holding the fresh/re-circulated air switch until the switch LED (light emitting diode)'s flash 3 times. The air intake door will now remain closed until the next drive cycle.
The ATC (automatic temperature control) module controls the position of the air intake door by providing LIN (local interconnect network) bus messages to the air intake door stepper motor. A Hall effect sensor, located within the stepper motor, informs the ATC (automatic temperature control) 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 (left-hand) and RH (right-hand) 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 (automatic temperature control) 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 (automatic temperature control) 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 (left-hand) and RH (right-hand) sides of the cabin.
NOTE:
The driver's side temperature setting has priority over the passenger's side temperature setting.
The temperature blend doors are mounted on the LH (left-hand) 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 (automatic temperature control) module controls the position of the temperature blend doors by providing LIN (local interconnect network) bus messages to the blend door stepper motors. Hall effect sensors located within the stepper motors inform the ATC (automatic temperature control) module that movement of the stepper motors is taking place.
Blower Motor Control - Dual Zone Automatic System
Blower motor speed is controlled automatically by the ATC (automatic temperature control) 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 (light emitting diode) located in the center of the rotary controller will extinguish.
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 (automatic temperature control) module varies the speed of the blower motor in line with its 'comfort' algorithm to maintain the required cabin temperature. The ATC (automatic temperature control) module will also vary the blower motor speed to compensate for the ram effect on intake air produced by forward movement of the vehicle.
The operation of the blower motor is controlled by the ATC (automatic temperature control) module via the blower motor control module. The ATC (automatic temperature control) module provides a PWM (pulse width modulation) signal to the blower motor control module based on the required blower speed. The blower motor control module interprets the PWM (pulse width modulation) signal as a blower motor speed and controls the voltage to the blower motor accordingly.
Air Distribution Control - Dual Zone Automatic System
Air distribution into the cabin is controlled automatically by the ATC (automatic temperature control) 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.
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 (light emitting diode) and allow the ATC (automatic temperature control) module to control air distribution in line with its 'comfort' algorithm.
Air distribution is controlled by 2 air distribution doors. The ATC (automatic temperature control) module controls the position of the air distribution doors by providing LIN (local interconnect network) bus messages to the door stepper motors. Hall effect sensors located within the stepper motors inform the ATC (automatic temperature control) module that movement of the stepper motors is taking place.
A/C (air conditioning) - Dual Zone Automatic System
Pressing the 'A/C' momentary switch in the control panel will switch off the A/C (air conditioning) system. When selected, the ATC (automatic temperature control) module will transmit a message over the high speed CAN (controller area network) bus to the ECM (engine control module) requesting the A/C (air conditioning) compressor is disabled. The ECM (engine control module) disables the compressor by de-energizing the A/C (air conditioning) compressor control relay located in the BJB (battery junction box). The 'A/C' tell-tale LED (light emitting diode) in the switch will illuminate to inform the vehicle occupants that the system is in 'A/C'
mode.
When 'A/C' mode is deselected, 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 'A/C' switch will extinguish the 'A/C' LED (light emitting diode). When it is in 'OFF' mode, the ATC (automatic temperature control) module sets the blower motor speed to 0. Air distribution into the cabin will remain as previously selected. All LED (light emitting diode)'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 'A/C' switch returns the system to normal (A/C (air conditioning)) operation and illuminates the 'A/C' LED (light emitting diode). The system can be returned to automatic operation at any time by pressing the 'AUTO' switch mounted in the central (blower motor) rotary controller.
Programmed Defrost
The function is selected by pressing the 'MAX' momentary switch on the control panel. When selected, the ATC (automatic temperature control) 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 'MAX' momentary switch a second time.
NOTE:
Blower motor speed can be adjusted without terminating programmed defrost.