The relay T5 in the engine compartment junction unit B1controls the compressor engagement circuit.The supply for the relay arrives via the line for the CVM maxifuse located on the battery, connector B99, via the line for the specific fuse F19 in the engine compartment junction unit B1. See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT.The climate control system control unit M70sends - from pin 36 - the enablement signal for engaging the compressor, to the 4 stage pressure switch K10: if the pressures in the coolant circuit are correct, the signal leaves the pressure switch and reaches the engine management control unit M10, pin 40 of connector A. On the basis of its internal control logic, the control unit M10sends the command - from pin 7 of connector A - to engage the compressor which energizes the relay T5 so that the air conditioning compressor engagement solenoid L20 is operated at a voltage of 12 V .