The relays T6and T7of the engine compartment junction unit B1manage the engagement of the fan N11at two speeds: the coils are supplied by the ignition-operated line (15/54) whilst the power lines are protected by fuses F6 and F7, in the engine compartment junction unit B1...If the engine coolant reaches an initial temperature level, or the 4 stage pressure switch K10signals to the control unit M10pin 9 of connector A - that the initial pressure level has been reached, then the control unit M10sends a signal from pin 50 of connector A - to the 1st fan speed relay T6, which then sends the power supply to the fan N11via the additional resistance O10the fan turns at the first speed (slow).If the engine coolant reaches a higher temperature level, or the 4 stage pressure switch K10signals to the control unit M10pin 41 of connector A that the higher pressure level has been reached, then the control unit M10sends a signal from pin 62 of connector A - to the 2nd fan speed relay T7, which then sends the power supply to the fan N11directly: the fan turns at the maximum speed.