Radiator fanRadiator fan  - Cooling system - Checking and topping up fluids - General maintenance - Audi S5 Owner's Manual - Audi S5

The radiator fan can start running spontaneously.

The radiator fan is driven by the engine via a poly V-belt. The speed of the fan is varied by a viscous clutch according to the temperature.

There is also an auxiliary electric fan, which cuts in automatically whenever the temperature of the coolant and the engine compartment rises above a certain level.

The auxiliary fan can continue to run for as long as 10 minutes after stopping the engine Ц even after the ignition is switched off. It may also start running suddenly ⇒ a while if after a while if
Х residual heat raises the coolant temperature, or
Х the hot engine compartment is additionally heated up by the sun.

WARNING
When working in the engine compartment be aware that the radiator fan may start running suddenly Ц risk of injury.