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
B25
up to 2/99
or from fuse
F4
of the additional fuse box
B98A
from
2/99; 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 electro-magnet 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 21 of connector
E).
According to its own internal control logic,
the control unit
M10
sends the command to engage the compressor
(from pin 4 of connector E) which energizes the relay
J20
.