Functional Description

Functional Description

• up to chassis no. 406517

Two fans P2a and P2b warrant the necessary ventilation of the cooling air for the engine and air conditioning system condenser radiator.

N.B.: the two fans are set in parallel and they are always operated together, following the same logic.

The two fans are always supplied by battery voltage: the first one (P2a) has the line protected by fuse F14 of fusebox G1; the second one (P2b) is protected by floating fuse Q39 (30A) which protects the whole system; they are therefore operated by an earth signal: this signal arrives directly (2nd speed) or through the additional resistance O22 (1st speed) fitted with a thermal safety fuse.

The delaying device Q42, in group Q41, controls the gradual turning on of the fans which are operated at two different speeds also via two relay I99b and I100, also part of group Q41.

The delaying device works according to the following logic:

The "key-operated" voltage (line protected by fuse F17 of G1) supplies the coil and electronic devices of the delaying device Q42 -pin 85, and relay I99b, while relay I100 is supplied by the battery voltage through floating fuse Q39 (30 A) and fuse Q66 (3 A) in group Q41. The coil of delaying device Q42 is energized by an earth signal -pin P- which leads from the trinary pressure switch Q20: this causes an earth signal to be sent immediately - pin 30 - to energize relay I99b which sends the earth to the two engine cooling fans P2a e P2b through the additional resistance O22: 1st speed)

After approx. 8-12 seconds, if the signal from the trinary persists, the delaying device operates the second speed with an earth signal from: pin 86, which energises relay I100 which sends the earth command directly to the two engine cooling fans P2a e P2b: 2nd speed.

When the signal from the pressure switch ceases the fan turns off immediately.

The two fans are operated at the two different speeds also by the two-level thermal contact L33 which controls the temperature of the coolant in the engine radiator: when a first level is reached, relay I99a is energized, which is located inside fusebox G1 in version "A" and outside it in version "B" - which sends the earth signal to the two engine cooling fans P2a and P2b through resistance O22: 1st speed.

If the second temperature level is reached, relay I100, is energized, which is located in group Q41, and this sends the earth signal directly to the two engine cooling fans P2a and P2b: 2nd speed.

Functional Description

• from chassis no. 406518

Two fans P2a and P2b ensure the necessary ventilation of the air for cooling the engine radiator and the conditioner system condenser.

N.B.: the two fans are in parallel, and are therefore operated together, always following the same logic.

The two fans are always supplied by battery voltage: the first (P2a) has the line protected by fuse F14 of fusebox G1; the second (P2b) is protected by wander fuse Q39 (30A) which protects the entire system; they are thus operated by an earth control signal: this signal arrives directly (2nd speed) or through the additional resistance O22 (1st speed), fitted with a safety fuse.

Engagement of the fans, operated at two different speeds through two relays I99 and I100 takes place according to the following logic:

The fans P2 are operated at two different speeds by the two-level thermal contact L33 which controls the temperature of the coolant in the engine radiator: when a first level is reached relay I99 is energised which sends the earth control signal to the fans P2 via resistance O22: 1st speed

If the second temperature level is reached, relay I100 is energised which sends the earth control signal directly to the fans P2: 2nd speed.

The two relays receive the key-operated supply; I100 is supplied by the line of fuse F4 of G1 (fusebox A) or fuse F15 (fusebox B).

Similarly the fans P2 are controlled at first speed by an earth signal leading from the trinary pressure switch Q20.