Principles of microclimate operation (Freelander 2)

Air intake control

Single-zone system with manual control

The air supply source is controlled manually by pressing the fresh/recirculated air switch located on the control panel. When the switch is pressed, the ATC module turns on the LED in the switch and closes the air intake flap. A second press of the switch causes the ATC module to turn off the LED in the switch and open the air intake flap, allowing fresh air to enter the cabin.

NOTE: The ATC module reduces the amount of fresh air entering the passenger compartment to reduce the effects of ram air caused by the forward motion of the vehicle.

When the air recirculation mode is selected, the ATC module returns the air intake flap to the open position after a 3-minute period. This helps prevent fogging in the cabin. The 3-minute air recirculation time interval can be cancelled by pressing and holding the fresh/recirculated air switch until the switch flashes three times. The air intake flap will now remain closed until the next driving cycle.

The ATC module controls the position of the air intake flap by sending messages via the LIN bus to the air intake flap stepper motor. A Hall sensor located in the stepper motor informs the ATC module that the stepper motor is moving.

Dual-zone automatic system

The air supply source is controlled automatically unless overridden by pressing the fresh/recirculated air switch located on the control panel. During automatic control, the ATC module determines the desired air intake flap position using its "comfort" algorithm based on input signals from the outside temperature sensor and the interior temperature sensor.

When the vehicle first enters power mode 6 (ignition on), the LED indicator on the fresh/recirculated air switch lights up and the air intake source begins to be automatically controlled by the ATC module. The ATC module will control the air intake source according to the outside temperature and the desired cabin temperature. The air intake flap will open, allowing fresh air to enter the cabin, although a small amount of recirculated air will also be present.

NOTE: The ATC module reduces the amount of fresh air entering the passenger compartment to reduce the effects of ram air caused by the forward motion of the vehicle.

A single press of the fresh/recirculated air switch will turn off the indicator. The ATC module now closes the air intake flap and provides only recirculated air into the cabin for a 3-minute period. After this period, the ATC module returns the air intake flap to automatic control. This helps prevent fogging in the cabin.

A second press of the fresh/recirculated air switch also returns the air intake source to automatic control and turns on the indicator lamp.

The 3-minute time interval for air recirculation can be cancelled by pressing and holding the fresh/recirculated air switch until the switch flashes three times. The air intake flap will now remain closed until the next driving cycle.



The ATC module controls the position of the air intake flap by sending messages via the LIN bus to the air intake flap stepper motor. A Hall sensor located in the stepper motor informs the ATC module that the stepper motor is moving.

Dual-zone automatic system with pollution sensor

The air supply source is controlled automatically unless overridden by pressing the fresh/recirculated air switch located on the control panel. During automatic control, the ATC module determines the desired position of the air intake flap using its "comfort" algorithm based on input signals from the outside temperature sensor, the interior temperature sensor and the pollution sensor.

NOTE: The ATC module reduces the amount of fresh air entering the passenger compartment to reduce the effects of ram air caused by the forward motion of the vehicle.

When the vehicle first enters power mode 6 (ignition on), the 'AUTO' LED indicator on the fresh/recirculated air switch illuminates and the air intake source begins to be controlled automatically by the ATC module. Pressing the fresh/recirculated air switch once will turn off the 'AUTO' indicator and turn on the 'MAN' indicator. The ATC module now closes the air intake flap and provides only recirculated air into the cabin for a 3 minute period. After this period, the ATC module returns the air intake flap to automatic control. This helps prevent fogging in the cabin.

A second press of the fresh/recirculated air switch will turn off both the 'AUTO' and 'MAN' indicators. The ATC module will now control the air intake source according to the outside temperature and the desired cabin temperature. The air intake flap will open, allowing fresh air to enter the cabin, but a small amount of recirculated air will also be present. The amount of recirculated air is determined by the ATC module using its 'comfort' algorithm based on input signals from the outside temperature sensor and the cabin temperature sensor.



Pressing the fresh/recirculated air switch a third time returns the air intake source to automatic control and turns on the 'AUTO' indicator.

The 3-minute time interval for air recirculation can be cancelled by pressing and holding the fresh/recirculated air switch until the switch flashes three times. The air intake flap will now remain closed until the next driving cycle.

The ATC module controls the position of the air intake flap by sending messages via the LIN bus to the air intake flap stepper motor. A Hall sensor located in the stepper motor informs the ATC module that the stepper motor is moving.

Air temperature control

Single-zone system with manual control

The interior temperature is selected by turning the left knob to the desired position. Turning the knob counterclockwise decreases the temperature of the air coming out of the heater; turning the regulator clockwise increases the temperature of the air coming out of the heater.

Maximum heating and cooling are represented on the control panel by red and blue dots respectively. When maximum heating or cooling is selected, the "comfort" algorithm in the ATC module adopts the appropriate strategy for air source, air distribution and fan speed to maintain maximum heating or cooling in the cabin.

The ATC module controls the temperature of the air leaving the heater by changing the position of the temperature mixing flap. The temperature mixing flap directs a portion of the cooled air from the evaporator through the heater core to provide the desired outlet temperature. The ATC module controls the position of the temperature mixing flap by providing LIN bus messages to the mixing flap stepper motor. A Hall sensor located in the stepper motor informs the ATC module that the stepper motor is moving.

Dual-zone automatic system

Dual-zone systems have two rotary heating controls that provide individual climate control for the left and right sides of the cabin. Temperature selection can be made by turning the control according to the desired temperature marked on the control panel. Turning either control beyond the 16°C mark initiates the maximum cooling strategy; turning any control beyond 28°C initiates the maximum heating strategy.

NOTE: Maximum cooling or heating can only be achieved if both rotary controls are set to the same position.

The ATC module is able to maintain a constant temperature on both sides of the cabin by monitoring the feedback from the cabin temperature sensor. Until any manual override is selected, the ATC module will automatically control the air intake source, cabin air distribution and fan speed to maintain the desired temperature values.

Dual-zone systems have two temperature mixing flaps that provide individual temperature control for the left and right sides of the cabin.

NOTE: The driver side temperature setting takes priority over the passenger side temperature setting.

The temperature mixing flaps are mounted on the left side of the heater and direct a portion of the cooled air from the evaporator through the heater core to provide the required outlet temperature. The ATC module controls the position of the temperature mixing flaps by sending messages via the LIN bus to the stepper motors of the mixing flaps. Hall sensors located in the stepper motors inform the ATC module that the stepper motors are moving.

Electric fan control

Single-zone system with manual control

The speed of the electric fan is set by turning the right control to the desired position. The right rotary control allows you to select 14 speeds of the electric fan. Turning the control completely counterclockwise turns off the electric fan.

The blower fan is controlled by the ATC module via the blower fan control module. The ATC module provides the blower fan control module with a pulse-width modulated (PWM) signal based on the selected blower speed. The blower fan control module interprets the PWM signal as blower fan speed and controls the voltage supplied to the blower fan accordingly.

Dual-zone automatic system

The speed of the electric fan is controlled automatically by the ATC module until manual operation is requested. Manual correction of the electric fan speed can be made by turning the central rotary control to the required position. The rotary control allows manual selection of 7 speeds of the electric fan. Turning the control completely counter-clockwise switches off the electric fan. When manual correction is made, the 'AUTO' indicator located in the center of the rotary control goes out.

NOTE: The center rotary control contains two LEDs. When the blower motor is under automatic control, the upper (round) LED will be illuminated. When the cabin air distribution is under automatic control (see below), the lower (rectangular) LED will be illuminated.

The blower motor can be returned to automatic control by pressing the 'AUTO' switch located in the centre of the rotary control. In automatic control, the ATC module varies the blower motor speed according to its 'comfort' algorithm to maintain the desired cabin temperature. The ATC module also varies the blower motor speed to compensate for the effect of the incoming air on the air intake created by the vehicle's forward movement.



The blower fan is controlled by the ATC module via the blower fan control module. The ATC module provides the blower fan control module with a PWM signal based on the desired fan speed. The blower fan control module interprets the PWM signal as fan speed and controls the voltage supplied to the blower fan accordingly.

Air distribution control

Single-zone system with manual control

The air distribution entering the passenger compartment can be adjusted by turning the central rotary control to the desired position. The ATC module adjusts the position of the air distribution flap to the desired position by sending messages via the LIN bus to the air distribution flap stepper motor. A Hall sensor located in the stepper motor informs the ATC module that the stepper motor is moving.

Dual-zone automatic system

The air distribution in the passenger compartment is controlled automatically by the ATC module, unless manual operation is requested. Manual override can be made by pressing the relevant momentary air distribution switch on the control panel. When manual operation is requested, the 'AUTO' indicator located in the centre of the blower motor rotary control goes out.

NOTE: The center rotary control contains two LEDs. When the blower motor is under automatic control (see above), the upper (round) LED will be illuminated. When the cabin air distribution is under automatic control, the lower (rectangular) LED will be illuminated.

The air distribution can be returned to automatic control by pressing the 'AUTO' switch located in the centre of the blower motor rotary control. This causes the 'AUTO' indicator to come on and allows the ATC module to control the air distribution according to its 'comfort' algorithm.



The air distribution is controlled by two air distribution flaps. The ATC module controls the position of the air distribution flaps by sending messages via the LIN bus to the stepper motors of the flaps. Hall sensors located in the stepper motors inform the ATC module that the stepper motors are moving.

ECON

Single-zone system with manual control

Pressing the momentary 'ECON' switch on the instrument cluster turns the A/C system off. When selected, the ATC module also sends a message over the high speed CAN bus to the ECM to request that the A/C compressor be turned off. The ECM turns the compressor off by turning off the A/C compressor control relay located in the BJB. The indicator in the switch will turn on to alert vehicle occupants that the system is in 'ECON' mode.

When 'ECON' mode is selected, temperature control is still maintained, but there is no cooling of the intake air. The minimum temperature of the air leaving the system will be the outside air temperature with the addition of heat collected in the air intake tract.

A/C can be turned back on by pressing the 'ECON' switch again. This also causes the 'ECON' indicator to turn off.

Vehicles equipped with the Stop/Start system - starting from 2010 MY

From MY 2010 onwards the 'ECON' switch will be labelled with the letters 'A/C'. This is to avoid confusion with the 'Eco' switch which controls the 'Stop/Start' and 'Gear Shift Sensor' systems. For further information please refer to the chapter: Starting System (303-06C Starting System - 2.2L Duratorq - Td4, Vehicles manufactured from 03/2009 onwards, Description and Function).

Two-zone system with automatic control

Pressing the momentary 'ECON/OFF' switch on the instrument cluster turns off the A/C system. When selected, the ATC module also sends a message over the high speed CAN bus to the ECM to request that the A/C compressor be turned off. The ECM turns the compressor off by turning off the A/C compressor control relay located in the BJB. The 'ECON' indicator in the switch will turn on to alert vehicle occupants that the system is in 'ECON' mode.

When 'ECON' mode is selected, temperature control is still maintained, but there is no cooling of the intake air. The minimum temperature of the air leaving the system will be the outside air temperature with the addition of heat collected in the air intake tract.

Pressing the 'ECON/OFF' switch again will turn off the 'ECON' indicator and turn on the 'OFF' indicator. In the 'OFF' mode, the ATC module sets the electric fan speed to 0. The air distribution in the cabin will remain at the pre-selected setting. All LEDs on the control panel will go out, although the night-time lighting will remain active.

NOTE: When in the 'OFF' mode, the heated seats, heated windshield and heated rear window functions are still available.

Pressing the 'ECON/OFF' switch a third time returns the system to normal operation (A/C) and turns off the 'OFF' indicator. The system can be returned to automatic operation at any time by pressing the 'AUTO' switch located in the center rotary control (electric blower).

Vehicles equipped with the Stop/Start system - starting from 2010 MY

From MY 2010 onwards the 'ECON' switch will be labelled 'A/C'. This is to avoid confusion with the 'Eco' switch which controls the 'Stop/Start' and 'Gear Shift Sensor' systems. For more information, refer to the chapter: Starting System (303-06C Starting System - 2.2L Duratorq - Td4, Vehicles manufactured from 03/2009 onwards, Description and Function).

Programmed de-icing

The programmed defrost feature is only available on vehicles equipped with dual zone heating, ventilation and A/C. The feature is selected by pressing the momentary 'PROG' switch on the control panel. When selected, the ATC module provides maximum windshield defrost/fogging by configuring the system as follows:

• 'AUTO' mode is off
• Setting the air intake to fresh air
• Adjusting the air distribution to supply air to the windshield
• Setting the speed of the electric fan to maximum
• Heated windshield is on
• Rear window heating is on

When programmable defrost is selected, the set temperature will remain unchanged. Programmable defrost can be cancelled in any of the following ways:

• Pressing any momentary air distribution switch
• Pressing the 'AUTO' switch located in the centre of the rotary control of the electric fan
• Pressing the momentary 'PROG' switch a second time

NOTE: The blower fan speed can be adjusted manually without disabling the programmable de-icing feature.

Heated windshield

The heated windscreen function consists of two heating elements, left and right, bonded between the layers of glass. The system is activated by pressing a momentary switch located on the instrument panel. Once selected, the ATC module transmits a heating request via the high speed CAN bus to the CJB. Upon receipt of the message, the CJB energizes the heated windscreen relay located in the BJB, providing ground to the relay coil. The energized relay provides battery voltage to both heating elements. After 4 minutes, the ATC module removes the heated windscreen request. The CJB then disables the heated windscreen, removing ground to the relay coil.

The ATC module requests operation of the heated windshield only when the engine is running. The engine status signal is sent to the ATC module from the ECM via the high speed CAN bus.

Rear window heating

The heated rear window feature consists of a single heating element bonded to the inside surface of the window. The system is activated by pressing a momentary switch located on the instrument panel. Once selected, the ATC module transmits a heating request via the high speed CAN bus to the CJB. Upon receipt of the message, the CJB energizes the heated rear window relay located in the Auxiliary Junction Box (AJB), providing ground to the relay coil. The energized relay provides battery voltage to the heating element. After 12 minutes, the ATC module removes the heating request. The CJB then disables the heated rear window, removing ground to the relay coil.

The ATC module requests operation of the rear window defroster only when the engine is running. The engine status signal is supplied to the ATC module from the ECM via the high speed CAN bus.

Heated exterior rear view mirrors

The operation of the heated outside rear view mirrors is fully automatic and does not require any command from the driver. The heated outside rear view mirrors are active when the outside air temperature is below 5°C and the engine coolant temperature is below 65°C. The outside air temperature and engine coolant temperature values are supplied by the ECM via the high-speed CAN bus. Upon receiving these temperature values, the CJB determines whether the heated outside rear view mirrors are required.

The CJB requests heated outside rear view mirrors by sending a message via the high speed CAN bus to the passenger and driver door modules. The door modules provide power and ground to the heating elements of the respective outside rear view mirrors. When the outside temperature and engine coolant temperature rise above the previously set values, the CJB sends a message via the high speed CAN bus to the door modules, canceling the heating request.

Heated seats

The seat heating system is controlled by the ATC module upon receipt of a request for heating from one of the momentary seat heating switches located on the instrument panel. The switches are located in the left and right rotary controls. Pressing the seat heating switch once initiates low-level heating and turns on the indicator lamp. Pressing the switch a second time initiates high-level heating and turns on both indicator lamps. Pressing the switch a third time turns off the seat heating.

Requests to turn on the seat heating are transmitted from the ATC module via the LIN bus to the seat heating control modules. Each of the two seat heating control modules is installed under the corresponding front seat. The seat heating control modules provide power to the seat heating elements and temperature sensors located in the seat cushion.

The seat heating control module supplies a 5 V reference voltage to the seat heating function temperature sensor. The seat heating function temperature sensor is an NTC thermistor. By monitoring the feedback voltage, the control module can calculate the seat temperature. If the temperature rises above the set temperature, the control module turns off the heating elements.