Why can't the fan of Volkswagen Touareg be turned off when the air conditioner is on?

[DiPaul]

This situation is mostly caused by a faulty thermostat or the absence of this sensor's function. The following details the reasons: Lack of coolant in the radiator: If the fan keeps running, first check whether the radiator is short of coolant, which may cause overheating. If there is a lack of coolant, check for any leaks: water pump, pipelines. Water in the engine oil: Check whether there is water in the engine oil and the combustion condition of the spark plugs, which can also determine whether coolant has leaked into the cylinders. Check whether there is air trapped in the water circulation system, causing poor circulation. Dirty radiator: Check whether the surface of the radiator is too dirty, leading to poor heat dissipation. Check whether there are scale oxides inside the radiator, causing poor circulation. Finally, check whether the temperature control switch is broken and remains powered on.