| Pos. | spare part no | Name |
| 1 | - | Refrigerant pressure sensor |
| 2 | - | Interior humidity sensor (in the presence of) |
| 3 | - | Air conditioning compressor (A/C) (i6 engine shown) |
| 4 | - | Engine coolant temperature sensor (EATING) |
| 5 | - | Outdoor temperature sensor |
| 6 | - | Air intake stepper motor |
| 7 | - | Pollution sensor (in the presence of) |
| 8 | - | Stepper motor for air supply to the windshield (de-icing) |
| 9 | - | Stepper motor for right mixing temperature damper |
| 10 | - | Solar radiation sensor |
| 11 | - | Cabin air temperature sensor |
| 12 | - | Temperature control module (ATC) |
| 13 | - | Evaporator temperature sensor |
| 14 | - | Stepper motor for left mixing temperature damper |
| 15 | - | Blower fan motor control module |
| 16 | - | Stepper motor for air supply to the face/footwell |
| 17 | - | Electric blower fan |
The climate control system integrates heating, ventilation and A/C systems. There are two main climate control systems:
- single zone system with manual control
- two-zone system with automatic control
The climate control functions of both systems are controlled by the ATC module. The ATC module is installed in the center console and contains both system software and controls.
The ATC module works in conjunction with a variety of other vehicle control modules, including the engine control module (ECM), which manages multiple climate control subsystems by receiving requests from the module.
The single zone climate control system has manual control of air temperature, air distribution and air source, although there are a small number of automatic control functions in the ATC module software. In response to incoming system signals, the ATC module controls the three stepper motors mounted on the heater assembly. The stepper motors adjust the position of the air temperature, air distribution and air source dampers accordingly.
The two-zone microclimate control system has automatic control of air temperature, air distribution and fan speed. The ATC module is also able to manage individual temperature requests from both the driver's and passenger's side.
NOTE: The ATC module can only maintain a maximum temperature difference between two compartments of approximately 3ºC. This is due to the movement and mixing of air inside the cabin.
The dual-zone climate control system has two additional sensors; cabin air temperature sensor and solar radiation sensor. The cabin air temperature sensor provides temperature feedback, allowing the ATC module software to maintain a constant cabin air temperature. The solar radiation sensor provides a reading of the intensity of solar radiation falling on the vehicle's occupants and allows the ATC module to adjust the performance of the climate control system accordingly.
Higher specification versions of the dual zone climate control system are also available. These systems have two additional sensors; pollution sensor and humidity sensor in the cabin.
The pollution sensor detects pollutants entering the passenger compartment, allowing the ATC module to respond by changing the position of the air intake damper. The interior humidity sensor calculates the likelihood of fogging up the windshield. The ATC module monitors the signal from the cabin humidity sensor and adjusts the blower speed, air distribution and A/C compressor output accordingly.
Vehicles equipped with the system «Stop/Start»
For system support «Stop/Start» a number of corrections were also made to the logic and operation of the microclimate control system in the cycle «Stop/Start»:
- maintaining the comfort of the driver and passengers
- windshield fogging prevention
- saving battery power
This is achieved by monitoring the ATC module (automatic climate control) and, if necessary, changing the various climate control functions in the Stop/Start cycle. For more information, see the chapter: Starting system (303-06C Starting system - 2.2L Duratorq - Td4, Vehicles built from 03/2009, Description and function).
To maintain the temperature in the car interior with the engine off in the mode «Stop/Start», an auxiliary electric coolant pump has been added to the cooling system, which ensures the passage of liquid through the passenger compartment heater radiator. The pump is connected directly to the engine control unit. On vehicles with an oil-fired heater installed, the heater coolant pump is used and activated by the heater. For more information, see the chapter: Starting system (303-06C Starting system - 2.2L Duratorq - Td4, Vehicles built from 03/2009, Description and function).
NOTE: From MY 2010 the 'ECON' switch will be labeled 'A/C'. This is to prevent confusion with the 'Eco' switch that controls the systems «Stop/Start» And «Gear shift sensor».
ATC module
The ATC module is installed in the center console and integrated with the control panel. The module works in combination with the ECM to control all aspects of HVAC. The 18-pin electrical connector on the back of the module provides wired, CAN bus, and LIN bus connections for interfacing with A/C system components and other vehicle control modules. For more information, please refer to the chapter: Communication Network (418-00 Communication network of modules, Description and principle of operation).
There are six different ATC modules depending on the vehicle specification (two single-zone and four two-zone). Vehicles with a low level of equipment ("low series") have three rotary controls and three top-mounted momentary switches to control the quality, temperature and air distribution in the cabin. Vehicles with a high level of equipment ("high series") have three rotary controls, six top-mounted momentary switches and two dual function switches to control cabin air quality, temperature and distribution.
In addition to the A/C system, the ATC module also controls the following functions:
- Seat heating
- Rear window heating
- Heated windshield
- Heated exterior mirrors
See the section below for more information "Principle of operation".
Compressor solenoid valve
| Pos. | spare part no | Name |
| 1 | - | Compressor solenoid valve. |
The compressor solenoid valve is integrated with the A/C compressor. Solenoid valve operation is controlled by the ECM using pulse-width modulated signals (PWM) various levels. By controlling the flow of refrigerant through the compressor, the solenoid valve can control the operating temperature of the evaporator and the humidity in the cabin by changing the pressure in the A/C system.
NOTE: The A/C compressor solenoid valve is only fitted to i6 petrol vehicles.
For more information, see the chapter: Air conditioning (412-01 Climate control, Description and principle of operation).
Refrigerant pressure sensor
The refrigerant pressure sensor provides the ECM with an input signal for the pressure in the high pressure circuit of the refrigerant system. The refrigerant pressure sensor is located in the refrigerant line between the condenser and expansion valve.
The ECM provides a 5 V reference to the pressure sensor and receives a voltage return signal ranging from 0 to 5 V, depending on system pressure. The ECM uses the signal from the sensor to protect the refrigerant system from pressure peaks.
If the pressure in the refrigerant system exceeds the minimum or maximum pressure limits, the ECM will:
- turn off compressor A/C (TD4 vehicles)
- reduce A/C compressor flow (i6 cars)
If reducing the A/C compressor flow does not bring the system back into the optimum pressure range, the ECM in the i6 engine will shut off the A/C compressor.
The ECM continuously sends a pressure signal to the refrigerant system to the ATC module. The signal is transmitted from the ECM to the central electrical junction box (CJB) via high-speed CAN bus. The CJB serves as a gateway and transmits the pressure signal to the ATC module via the medium speed CAN bus.
If the pressure in the refrigerant system rises above the maximum pressure limit, the ATC module increases the amount of recirculated air entering the passenger compartment. This helps depressurize the refrigerant system and thus avoids the need to shut down the A/C compressor.
Evaporator temperature sensor
The evaporator temperature sensor is an NTC thermistor (NTC). The sensor is mounted on the left side of the heater housing and measures the temperature of the cooled air as it passes through the evaporator. The sensor receives a reference supply voltage of 5 V from the ATC module. By monitoring the feedback voltage, the ATC module can calculate the resistance of the sensor and therefore the temperature of the evaporator.
Cabin temperature sensor
The interior temperature sensor is an NTC thermistor with an electric fan. The sensor is located behind the grill on the dashboard on the driver's side next to the steering column.
NOTE: The interior temperature sensor is only fitted to vehicles with a dual-zone automatic climate control system.
The electric fan is powered by the ATC module and draws air from the passenger compartment through the grill above the thermistor. The thermistor receives a 5 V supply voltage reference from the ATC module. By monitoring the feedback voltage, the ATC module can calculate the cabin air temperature.
Interior humidity sensor
The interior humidity sensor is located inside the interior mirror and consists of three separate elements:
- Humidity sensor
- Air temperature sensor
- Windshield temperature sensor
NOTE: The interior humidity sensor is only available as an option.
The readings from these three sensors are combined to reduce the effect of moisture on the windshield.
The sensitive element of the humidity sensor is located under the nylon mesh cover. The sensor contains an element made of film capacitors on various bases. The dielectric separating the plates is made of a polymer that absorbs or evaporates moisture in proportion to the relative humidity of the air passing through the sensor. This causes a change in the capacitance of the sensor.
Humidity in the cabin is controlled by raising or lowering the evaporator temperature. Increasing the evaporator temperature increases the moisture content in the cabin air. Lowering the evaporator temperature reduces the moisture content in the cabin air.
The sensor capacitance data, together with both temperature values, is sent as messages on the LIN bus to the ATC module. The ATC module uses these signals to calculate the windshield air dew point. When the windshield temperature reaches or falls below this value, moisture may appear on the glass. At this point, the ATC module will:
- raise the temperature of the air leaving the heater
- adjust the position of the stepper motor to supply air to the windshield (de-icing)
- adjust the position of the air intake stepper motor
- reduce A/C compressor flow (i6 cars only)
- supply power to the windshield heating elements (in the presence of)
Outdoor temperature sensor
The outdoor temperature sensor is an NTC thermistor. It is installed in the left exterior rearview mirror. The sensor receives a 5 V supply voltage reference from the ECM. By monitoring the feedback voltage, the ECM can calculate the resistance of the sensor and therefore the outside air temperature. The ECM transmits the outside air temperature via the high speed CAN bus. This value is sent by the CJB to the ATC module via the medium speed CAN bus.
Solar radiation sensor
The solar radiation sensor is installed in the center of the upper surface of the instrument panel. The sensor contains a photocell that provides the CJB with an input signal of the intensity of sunlight, equating to the effect of heating the passenger compartment with solar radiation.
The solar heating efficiency value is transmitted from the CJB to the ATC module via the medium speed CAN bus. The ATC module compensates for the effects of solar heating by adjusting the blower speed, outlet air temperature and air distribution to maintain the desired cabin temperature.
Pollution sensor
A pollution sensor allows the ATC module to monitor the outside air for the presence of hydrocarbon oxide (CO) and nitrogen oxides (NOx). The sensor is installed on the right side of the heater housing.
NOTE: The pollution sensor is installed as an option on vehicles with a dual-zone automatic climate control system.
The contamination sensor is powered by the battery electrical junction box when the ignition is on (BJB) and sends one of the following four signals to the ATC module based on the outside air quality:
- Static or reduced pollution levels
- Slight increase in pollution levels
- Mean increase in pollution levels
- Rapid or large increase in pollution levels
Based on the signal from the pollution sensor, the ATC module is able to control the intake air supply to reduce the entry of contaminants into the passenger compartment. This function is fully automatic but can be overridden by manually selecting the air source using the fresh/recirculated air switch on the control panel
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