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 from fuse
F4
of the additional
fuse box
B98A
; the relay is thus 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 3 of connector B).
According to its own internal control logic,
the control unit
M10
sends the command to engage the compressor
(from pin 32 of connector D) which energizes the relay
J20
.