223002770 - E5020 ENGINE COOLING - FUNCTIONAL DESCRIPTION (Climate control system, MY 2005)

The power supply for the fans N11 and N12 arrives directly from the battery via relays R6 and R7 housed in the engine compartment junction unit B01 through the line entering pin 1 connector A of the actual junction unit.The power supply for the relays is protected by fuses F7 for relay R7 and F6 for relay R6.They are energized by two distinct earth signal coming from the engine management control unit M10.The engine temperature sensor K36 measurs the temperature of the engine coolant and, if the values of this parameter are high, the control unit M10 sends an earth signal from pin 7 of connector A to the relay R6 (which manages the first fan speed) which energizes the coil. Relay R6 sends the power supply, operating the fans N11 and N12, in series, by means of the remote control switch J39, at the first speed (slow).The high pressure of the climate control system, detected by the 4 stage pressure switch or by the engine coolant reaching a high temperature, causes the second fan speed to be engaged.    See E6021 COMPRESSOR ENGAGEMENTIn this case the control unit M10 sends an earth signal from pin 8 connector A to relay R7 and, simultaneously, to remote control switch J39 which makes the power supply for the fans N11 and N12 available in parallel and both fans therefore operate at the second speed.