Ford Focus engine cooling fan

check coolant level first . If ok and not overheating , could just be faulty switch .

the cooling fan on your car will be linked to an electric sensor/switch, this can be found on the side of the radiator or on the water housing by the engine, the location depends on the engine type, this is easely replaced and it is not dear, any good autofactors should be able to help you out, this should sort out your problem.