Two electric cooling fans are fitted to all models, supplied with current through the ignition switch, cooling fan control unit located on the motor, temperature sensor, relays, and fuses or fusible link. The circuit is activated by the temperature sensor mounted in the outlet elbow at the bottom left-hand side of the radiator, except on 2.0 litre diesel and petrol engines, where the engine management ECU activates it according to the engine coolant temperature sensor. If a fan does not appear to work, first check the fuses and fusible links. If they are good, run the engine until normal operating temperature is reached, then allow it to idle. If the fan does not cut in within a few minutes, the cause may be the temperature sender, which can be checked by an Audi dealer using specialist diagnostic equipment. Check the motors by disconnecting the motor wiring connector and connecting a 12-volt supply directly to the motor terminals; if the motor is faulty, it must be renewed, as no spares are available. If the fan still fails to operate, check the cooling fan circuit wiring, ensuring each wire has continuity and that all connections are clean and free of corrosion. On models with a cooling fan control unit, if no fault can be found, it is likely that the cooling fan control unit is faulty, and testing should be entrusted to an Audi dealer or specialist; if the unit is faulty, it must be renewed. To remove the cooling fan assembly, switch off the ignition and all electrical consumers, then remove the plastic cover from the top of the engine. Undo the retaining screws and securing clips from the air filter housing and ducting, and remove it from in front of the battery tray. On some models, it may be necessary to move the lock/radiator carrier to its service position to allow for more room. On turbo models, release the securing clip and disconnect the hose from the left-hand side lower part of the intercooler. Disconnect the wiring plug for the cooling fan motors, unscrew the bolts securing the cooling fan shroud to the radiator, and withdraw it either upwards or downwards according to the model. To remove the fans and motors from the shroud, first disconnect and release the wiring plugs, then unscrew the nuts and remove the units.