Radiator Cooling Fan: Description and Operation

Engine Coolant Fan





the Coolant Fan is a nine bladed fan measuring 400 mm in diameter, driven by a 350 watt motor and controlled by the EMS2000. This system has two fan speeds.

the Engine Coolant Fan is controlled by the EMS2000 through a relay and relay pack at two different speeds, Low and High.

In addition to maintaining coolant temperature, the fan is used to cool the A/C refrigerant and where applicable, the ECVT gearbox oil.

the cooling fan operates on Low speed when the AC is switched on and the system pressure reaches 8 bar. Should the AC system pressure rise above 18 bar, the fan will automatically run on High speed.

For the engine coolant system the fan operates on Low speed at 105° C. When the temperature drops to 101° C the fan will switch off. High speed is switched on at 112° C and will remain on until the system coolant temperature drops by 4° C at which point the system will revert to Low speed fan.

the engine coolant fan is operated through two relays, a Low speed relay and a High speed relay. the Low speed relay is mounted in the engine compartment fuse box and is energized any time fan operation is needed (Both Low and High speed). the High speed relay is mounted on the fan housing in the relay pack. the relay pack contains the High speed relay and a voltage reducing resistor.

When Low speed fan operation is needed the EMS2000 energizes the Low speed relay. Voltage flows from the Low speed relay to the relay pack, through the voltage dropping resistor, enabling Low speed fan operation.

When High speed fan operation is needed, the EMS2000 energizes the High speed fan relay in the relay pack mounted on the fan housing. (the low speed relay remains energized). the fan is now run at full battery voltage and achieves high speed operation.

A diode is installed in the relay pack to prevent voltage feedback through the resistor.