The relay
J20
controls the compressor
engagment circuit.
The relay is supplied by the line controlled
by the ignition (INT/A) for relay
R1
protected by fuse
F15
:
both are housed in the junction unit
B1
.
The coil is supplied by the line from fuse
F2
of the additional fuse box B98 A, of the main injection relay J10;
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 11 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 54 of connector A.
According to its internal control strategy,
the control unit
M10 sends - from pin 28 of connector A - the
command to engage the compressor which energizes the relay J20.