The relay
J20
controls the compressor
engagement circuit.
The relay receives a supply from the line
controlled by the ignition (INT/A) for the relay
R1
protected
by fuse
F15
: both are housed in the junction unit
B1
.
The coil receives a supply controlled by
the ignition (15/54) from the line of fuse
F4
of the additional
fuse box
B98A
; the relay is energized by an earth signal
coming from the engine management control unit
M10
: in this
way the air conditioning compressor engagement electro-magnet
L20
is
operated through a voltage of 12 V.
Climate control unit
M70
(pin 7 of
connector A) sends a compressor enablement signal to four-stage
pressure switch
K10
. If circuit pressures are correct, the
signal leaves the pressure switch and reaches engine control unit
M10
.
(pin 21 of connector E).
According to its own internal control logic,
the control unit
M10
sends the command to engage the compressor
(from pin 4 of connector E) which energizes the relay
J20
.