323000436 - E5020 ENGINE COOLING - DESCRIPTION (Automatic air conditioning, Manual Air Conditioning)

DESCRIPTION

The vehicle is equipped with an engine cooling system comprising a two speed fan operated by the engine management control unit.The following parameters are taken into consideration for engine cooling: the temperature of the engine coolant and the pressure of the climate control system refrigerant fluid.The fan is activated at low speed as soon as the temperature of the engine coolant exceeds around 94 °C or the pressure of the refrigerant fluid exceeds a certain level. Whilst the second (higher) speed corresponds to the exceeding of the level of 102 °C or the second refrigerant fluid pressure level (about 21 bar).The shift from the second speed to the first speed takes place when the temperature goes below 99 °C (3 degrees lower to allow a hysteresis cycle) and the pressure of the refrigerant fluid is less than the second level. Whilst the fan is completely deactivated when the temperature of the coolant is below the level of 94 °C (and, at the same time, the pressure of the refrigerant fluid is below the first intervention level).If the engine is switched off and the temperature of the coolant is above a certain level, the fan continues working at the low speed for a preset time after which it switches off automatically.If the vehicle has a diesel engine there is a certain delay between the intervention level being exceeded and the activation (or deactivation) of the fan. This is because the engine management control unit automatically acts on the engine to produce a greater torque before making the ventilation device cut in or to decrease it before changing the fan rotation to a slower speed or turning it off.