E6020 Air conditioner

Description

The vehicle climate control system involves a duct/distributor unit with a heater. The air conditioning system includes the heater and has the function of producing cold, dehumidified air by switching on the compressor and the cooling system.

The climate control is operated by acting on the three knobs in the dashboard:

• the left knob controls mixing of hot and cold air;
• the right knob, mechanically operated via a cable, controls the opening of the flaps which regulate the distribution of air flows;
• the centre knob electrically controls the ventilation of the air at four different speeds;

The air recirculation button and the button for switching on the air conditioning compressor are located in the lower part of the control panel.

A dedicated control unit manages system operation by controlling:

• 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.

According to the setting, the control unit adjusts passenger compartment air intake speed by means of the fan motor and air temperature by a mixer actuator. 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 Wiring diagram E6021 COMPRESSOR ACTIVATION .

For more details Characteristic of working principle 5040 Air conditioner box and components .

Note

Recirculation brings about closing of windows Wiring diagram E3050 FRONT WINDOW MECHANISM and sun roof Wiring diagram E3060 SUN ROOF . The air conditioning control unit downloads a signal from the gas presence sensor and activates the recirculation function to prevent polluted air from being taken into the passenger compartment. When normal conditions are restored, the climate control system ECU resets recirculation to the position prior to function activation. Because recirculation is activated under these conditions, a command is sent for automatic closure of the windows Wiring diagram E3050 FRONT WINDOW MECHANISM and sun roof Wiring diagram E3060 SUN ROOF .

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 ECU is supplied by an ignition-operated line protected by a fuse in the underfacia control unit; the fan is supplied by a line protected by a specific engine bay control unit fuse.

Description of operation

Climate control control unit M70 is supplied when the ignition is turned on (INT/A) at pin 3 of a line protected by fuse F31 from underfacia junction unit B2.; it is supplied directly at pin 2 from a line protected by fuse F39 of underfacia control unit B2.

The supply for lighting the controls with the side lights on reaches pin 24 from the line protected by fuse F35 of underfacia control unit B2.

Pin 1 of M70 is earthed.

Recirculation actuator N82 is controlled by control unit M70, via pins 14, 15, 16 and 17.

The air mixing actuator N81 is controlled from control unit M70 from pins 23, 24, 25 and 26.;

The air distribution actuator N80 is controlled from control unit M70 via pins 19, 20, 21 and 22.

An electronic governor operates the fan N85 at different speeds via an earth control: it is ignition-operated (INT/A) via a line protected by fuse F31 from underfacia control unit B2. It receives a command signal from the control unit via pin 10 and returns a feedback signal to pin 18 of M70.

Fan N85 is supplied directly by a line protected by fuse F5 of engine bay control unit B11 of M70 and controls activation of compressor Wiring diagram E6021 COMPRESSOR ACTIVATION .

Pins 6 and 7 of control unit M70 connect to Body Computer M1 and node H44 via the CAN line and exchange the following signals:

• speedometer signal
• windscreen washer activation signal for recirculation activation
• window and sun-roof closure control
• battery voltage signal
• rear window activation signal

Wiring diagram

Components

Component location