The compressor activation circuit is controlled by relay R5, contained in engine bay junction unit B01.This is supplied directly by a line from the battery that enters at pin 1 of control unit connector A of the control unit and is protected by fuse F19.The coil of relay R5 is supplied by a signal from relay R9 that in turn receives a direct supply from the battery at pin 1 connector A.The power supply to the coil of relay R9 is ignition-operated (15/54) and is received via a line protected by fuse F16.Relays R9 and R5 are excited by an earth signal from engine management unit M10 respectively from pins 62 and 64 of connector A.In this way, control unit M10 controls the activation of air conditioner compressor L20 via relay R5.Engine compartment control unit M10 receives signals from 4 level pressure switch K10 to turn on the radiator fan:- operation at first speed from pin 14;- operation at second speed from pin 6;- air conditioner activation from pin 26.