The supply for the two fans
N11
and
N12
arrives
directly from the battery from the lines of the two maxifuses FAN1
and FAN2 of
B99
:the fans operate when they receive an earth
command.
The relays
J30
,
J31
and
J32
,
specific to the cooling system, receive supply to their coils from
the line controlled by the ignition (15/54) protected by fuse
F4
of
the additional fuse box
B98A
.
They are energized by an earth signal coming
from the engine control unit
M10
.
If the engine coolant temperature reaches
the first temperature stage, or the 4 stage pressure switch
K10
(pin
3) signals to the control unit
M10
that the first pressure
stage has been reached, then the control unit
M10
sends an
earth signal to the 1st speed fan relay
J30
which energizes
the coil. The relay then sends an earth which, via the additional
resistors
O10
and
O12
, operates both fans
N11
and
N12
which rotate at the first (slow) speed.
If the engine coolant reaches a higher temperature
level, or the 4 stage pressure switch
K10
(pin 6) signals
to the control unit
M10
that a higher pressure level has
been reached, then the control unit
M10
sends an earth signal
to the two 2nd speed fan relays
J31
and
J32
which
energize the coils. The two relays then send an earth directly
to the two fans
N11
and
N12
which rotate at maximum
speed.