2428098 - E6020 AIR CONDITIONING - Description (Two-zone climate control system)
Description
An automatic system manages the passenger
compartment climate control, i.e. temperature and ventilation with
recirculation and air flow orientation, with separate management of
the temperature for the left and right hand sides of the passenger
compartment.A dedicated control unit manages
system operation by controlling:
- air temperature at the driver/passenger vent;
- Air distribution to the vents.
- speed of the fan (varies continuously);
- activation of the compressor (air refrigeration circuit);
- activation of air recirculation;
- The MAX-DEF fast defrost function (i.e. a set of actions
which allow both the windscreen and the rearscreen to be demisted
quickly);
The control unit sets the above parameters
in order to adjust passenger compartment temperature to the required
level. The system controls are located outside the control unit housing.The following parameters/functions
can be modified manually:
- fan speed;
- distribution direction
- compressor disablement
- defrosting/demisting:
- recirculation.
Manual selections always take precedence
over automatic selections and are stored until the user deliberately
cancels the command, allowing the automatic device to take control over
the relevant function.The control unit downloads information
on interior and exterior temperature and climatic conditions via
special sensors.
- exterior temperature sensor, locate on the driver's side
door mirror. The sensor reading is downloaded by a control unit
on the door and filtered as necessary; it is then sent via the CAN
network to the climate control system ECU (to instrument panel and
other appliances).
- lower mixed air temperature sensor (right and left);
- upper mixed air sensors (right and left);
- sunlight sensor, which measures the sun's rays on the
windscreen;
- exhaust gas presence sensor (A.Q.S.: Air Quality Sensor):supplies
a signal when the air pollution index exceeds a preset level of
harmfulness. This signal turns on the recirculation to prevent polluted
air entering the passenger compartment;
- demisting sensor, which detects the presence of water
droplets (mist) on the inner surface of the windscreen; this information
turns on the relevant demisting strategy., which alters the air
and ventilation distribution pattern.
After processing the information, it adjusts
passenger compartment air intake speed by means of the fan motor
and air temperature by means of two mixer actuators (one for the right
side and one for the left). It also controls flow distribution via
another actuator and - lastly - the interior/exterior air recirculation
function via a final actuator.
When required, the ECU automatically activates
the cooling circuit and dehumidifies the air by operating the air
conditioner compressor
See E6021 COMPRESSOR ENGAGEMENT
.
For more details,
Characteristic of working principle 5040 AIR CONDITIONING CASING
AND COMPONENTS
.
The climate control system ECU receives
a signal from the body computer to indicate that the windscreen
washer is on and activates the recirculation function to prevent
the liquid detergent smell from entering the passenger compartment.The vehicle speed signal - received by the
CAN network - is used to filter outdoor temperature and adjust ventilation
and the dynamic air intake according to car speed.The body computer continually downloads
a battery voltage signal for comparison with its limit value. If
the recorded battery voltage is lower than the threshold, the computer cuts
in via the CAN network to send a signal to disable a series of appliances:
this includes the fan control.The climate control system control unit
is supplied by two lines, one direct and one controlled by the ignition,
protected by fuses in the underdashboard control unit. the fan is
supplied by a line protected by a special fuse and by a specific
relay in the engine compartment control unit.