Detection of contamination of a radiator or a radiator supplying air path

One aspect of the invention relates to a method of detecting contamination of a radiator or a radiator supplying air path. The cooler is preferably around the radiator in a motor vehicle. There is a fan for the supply of the cooler with a cooling air mass flow present. The fan is preferably an electric fan. By the contamination of the cooling air mass flow is impaired. According to the inventive method, the contamination is detected on the basis of a standing with the cooling air mass flow associated measurable fan size of the fan.