The special button (ice symbol) on the climate control system control unit switches on the air cooling and dehumidification circuit, activating the air conditioning compressor.

The above button enables the operation of the air cooling circuit, but the actual compressor activation is also dependent upon the activation of:

- the linear sensor, located on the coolant circuit that stops air conditioner activation if coolant pressure is too low or high;

- the Powertrain Control Module that excludes compressor operation in accordance with engine management mode; e.g. in the case of high engine temperatures or high engine load (sudden acceleration);

The button also only sends the control signal if the control knob for the different fan speeds is in a position other than "0".

For more details

  See descriptions 5040 AIR CONDITIONING CASING AND COMPONENTS 

The relay switch T05 for the engine compartment junction unit B001 controls the compressor engagement circuit.

The supply for the relay switch is via the line for specific fuse F19 of the engine compartment junction unit B001.

The power supply for the coil for relay switch T05 arrives from the ignition-operated line (INT) protected by fuse F51 of M001.

- on versions with MANUALLY OPERATED AIR CONDITIONING:

The button for engaging the compressor is located in control unit H080 and sends the signal to pin 49 of connector B of the Body Computer M001 which sends the enablement signal to the Powertrain Control Module M010 via the CAN.

Control unit H080 receives an ignition-controlled supply (INT) from the line protected by fuse F51 of M001.

The control signal is only sent if the control knob for the different fan N085 speeds is in a position other than "0".

  See E6020 AIR CONDITIONING 

The ideogram (ice symbol) is lit up when the button is pressed.

- on versions with AUTOMATIC AIR CONDITIONING the request to engage the compressor is sent by the climate control system control unit M070, via the CAN, to the Body Computer M001 which sends the enablement signal, via the CAN, to the Powertrain Control Module M010

According to its internal control logic, the control unit M010 sends the actual command to engage the compressor, from pin 29 of connector A, and relay switch T05 is energized: in this way the air conditioning compressor engagement electromagnetic coupling L020 is operated with a 12 V voltage.

If the linear sensor for the fans K120 signals to the control unit M010 - pin 10 of connector A - that the pressure value is too high or too low, then the control unit M010 excludes the engagement of the compressor.

The linear sensor K120 receives a power supply and reference earth from the Powertrain Control Module M010, pins 1 and 3 of connector A.