2429924 - E6021 COMPRESSOR ENGAGEMENT - Functional description

Functional description

Relay T5 of engine compartment junction unit B1 controls the compressor activation circuit The relay power supply passes through the line of dedicated fuse F19 of engine bay junction unit B1 The power supply to the coil of relay T5 arrives from main injection relay T9 and ignition-opeated line (15/54) protected by fuse F18, both located in engine bay control unit B1 See E5050  DIESEL ENGINES ELECTRONIC MANAGEMENT .

Functional description

Pressing the button in group H80, sends two signals:

• to the engine management control unit M10, at pin 40 of connector A; this signal 'passes through' the frost sensor K86 which does not supply the go ahead for the activation of the compressor if the temperature of the evaporator is too low;
• The second signal energizes the relay J34 coil which activates the first speed for the fan N85 , according to the description See E6020  AIR CONDITIONING.

Fan N85- supplied by ignition-operated line (INT/A) of relay T8 and dedicated fuse F8 of engine bay control unit B1 - is operated at the first speed in any case if the compressor activation request button is operated, even if control knob H81 is in position '0'. According to its internal control logic, the control unit M10 sends the command - from pin 46 of connector A - to engage the compressor which energizes the relay T5. The activation electromagnet of air conditioner compressor in L20 is therefore controlled at a voltage of 12V If the linear sensor for fans K120 indicates that the pressure level is too high or too low to control unit M10 - pin 54 of connector A, control unit M10 cuts out compressor activation. Linear sensor K120 receives a power supply and reference earth from the engine management control unit M10, pins 5 and 53 of connector A.