The supply for the fan
N11 arrives
directly from the battery from the line for the maxifuse B8: the fan therefore only works when it receives an earth command.
The relays
J30 and J31 have coils supplied by the line controlled by the ignition (15/54) protected
by fuse B25.
They are energized by an earth signal coming
from the engine control unit
M10.
If the engine coolant reaches a first temperature
level, or the 3 stage pressure switch
K5 (pin1) signals
to the control unit M10 (pin 20 of connector C)
that the first pressure level has been reached, then the control
unit M10 sends (from pin 23 of connector B) an earth signal
to the 1st fan speed relay J30, which energizes
the coil.
The relay then sends an earth signal which,
via the additional resistance
O10, operates the fan N11 which rotates at the first (slow) speed.
If the engine coolant reaches a higher temperature,
the control unit
M10 sends (from 45 of connector C) an
earth signal to the fan 2nd speed relay J31 which
energizes the coil.
The relay then sends an earth signal
directly to the fan
N11 which rotates at the maximum speed.