3315698 - E5020 ENGINE COOLING - Functional description (Automatic transmission)

Functional description

The power supply to fan N11 is controlled by two relays R7 (1. speed) and R6 (2. speed), located in relay control unit B3 . When fan N11 is supplied by relay R7 (1st speed), the supply line is subject to charge O11 , which reduces effective voltage and thus speed; is the fan is supplied by relay R6 (2nd speed) this is activated by maximum battery voltage, which therefore corresponds to maximum speed. Both relays are supplied with power directly from the battery - junction unit A5 - by a line protected by a special fuse F9 for R7 and F8 for R6 , all located in B3 .

They are energized by an earth signal coming from four-stage pressure switch K10 via the engine control unit M10.

• if the coolant temperature reaches the first temperature stage, or the 4-stage pressure switch K10 pin 1 - indicates to control unit M10 pin 9 of connector A - that the first pressure stage has been reached, control unit M10 sends a signal to 1st speed relay R7 from pin 50 of connector A.
• if the engine coolant reaches a higher temperature level, or the 4-stage pressure switch K10 pin 3 - indicates to control unit M1 pin 41 of connector A - that a higher pressure level has been reached, control unit M10 sends an earth signal to 2nd speed relay R6 from pin 62 of connector A.