The relay
J20
controls the compressor
engagment circuit.
The relay is supplied by relay
R1
:
line controlled by the ignition INT/A, protected by fuse
F15
:
both are housed in the junction unit
B1
.
The supply for the relay
R1 comes from
the direct line of the maxifuse J/B1 of B5, whilst the coil is supplied
by the ignition-operated line (INT/A): this line also supplies the control
switch in unit H81 .
via fuse
B27
.
The relay
J20
coil is suppiled by
the line protected by fuse
B39 See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT
.
Press the appropriate button on unit
H81
to sends a signal to 4-stage pressure switch K10:
This, in
turn, if the pressure in the circuit is correct, does not interrupt
the signal which reaches the engine control unit
M10
(pin
60 of connector A).
Control unit
M10
uses its own internal
software to send a signal (from pin 18 of connector A) to activate
the compressor which energizes the relay J20.
The relay operates the solenoid valve, at
12 V, which switches on the air conditioning compressor
L20
.
The fan
N85 operates at the first speed
if the button for engaging the compressor is pressed, except if
the control knob H81 is in position '0'
See
E6020
AIR CONDITIONING
.