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 receives a supply controlled by
the ignition (15/54) from the line of fuse
B25
; the relay
is thus energized by an earth signal coming from the engine management
control unit
M10
: in this way the air conditioning compressor
L20
engagement electromegnet is operated through a voltage
of 12 V.
The climate control control unit
M70
(pin
7 of connector A) sends the signal for enabling the engagement of
the compressor to the 4 stage pressure switch K10; if the pressures
in the circuit are correct, the signal leaves the pressure switch
and reaches the engine control unit
M10
(pin 40).
According to its internal control logic,
the control unit
M10
sends the effective command to engage
the compressor (from pin 32) which energizes the relay
J20
.