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 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 40 of connector A.
According to its internal control strategy,
the control unit
M10 sends - from pin 7 of connector A - the
command to engage the compressor which energizes the relay J20.