The relay
J20
controls the compressor
engagment 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 is supplied by the line from fuse
F2
for the additional fuse box B98 A for the main injection relay J10
therefore the relay is energized by an earth signal coming from
the engine management control unit M10: in this way the air conditioning
compressor L20 engagement electro-magnet 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 40 of connector A.
According to its internal control logic,
the control unit
M10 sends - from pin 7 of connector A - the command
to engage the compressor which energizes the relay J20.