Fiat 1998 Marea Weekend, Service Manual

Page: 148 / 846

Engine
Marea-Marea Weekend
® 1*
Fuel system 1998
range
10.
HEATING/VENTILATION SYSTEM MANAGEMENT
The injection-ignition control unit is connected operationally to the air conditioning system because:
1. a compressor activation request is received and appropriate action is taken (supplementary air);
2. compressor activation is enabled via pin 4 1 , when certain pre-established conditions are satisfied;
3. information on 4-level thermostat status is received through pins 21, 35, 48 and appropriate action is
taken (radiator fan activation).
With regard to point 1, if the engine is idling, the ECU increases the flow of air from the idle actuator
ahead of compressor activation while the actuator is restored to normal position with a delay in relation
to compressor de-activation.
With regard to point 2, the ECU automatically controls compressor de-activation:
- for a few seconds (timed de-activation):
- during high power demands on the engine (strong acceleration)
- engine take-off;
- as long as the following critical conditions persist:
- for coolant temperatures in excess of a set threshold
- for engine speeds less than 750 rpm.
K 7 , 5 A h
tit i l l
30 85 86 87
'•T s! U L_l
I
15/54
30 85 86 87
i
'is i i 'j-i i.
±
35
21
1. Climate control system fuse
2. Heating/ventilation system relay
3. Compressor electromagnetic coupling
supply relay
4. Compressor
5. Injection-ignition ECU
6. Pressure switch
7. Defrosting sensor
8. Injection-ignition control unit fuse
9. Ignition switch
10. Climate control system control unit
11. Power fuse box
12. Battery
14
Publication no. 506.763/09