199001404 - E5020 ENGINE COOLING - FUNCTIONAL DESCRIPTION (Automatic air conditioning, Manual air conditioning)

FUNCTIONAL DESCRIPTION

Relays T1 and T2 of engine compartment control unit B1 manage the activation of two speed fan N11: the coil power lines are protected by fuses F12 and F13 , also in engine compartment control unit B1 .Both are energized by an earth control signal coming from the engine management control unit M10.If the engine coolant reaches the first temperature level or linear sensor K120 indicates to the control unit M10 pin 5 or 39 of connector A - that a certain pressure level has been reached, control unit M10 sends a signal from pin 63 or 45 of connector A that excites the fan 1st speed relay T1, which then sends power to fan N11 via additional resistance O10 : the fan turns at the first speed (slow).The linear sensor K120 receives a power supply and reference earth from the engine management control unit M10, pin 3 or 53 and 15 or 5 of connector A.If the engine coolant temperature reaches a higher level or linear sensor K120 indicates to control unit M10 that a higher pressure level has been reached, then control unit M10 sends a signal from pin 59 or 46 of connector A to fan 2nd speed relay T2, which then sends power to fan N11 directly: the fan turns at the maximum speed.