There can be many causes and the problem needs to be properly diagnosed. This is not necessarily indicative of a cooling problem. Front end air flow goes down with slow/no speed. It is only a problem if you get too hot.
A hot running car needs to be properly diagnosed. It may be caused by a defective or undersized radiator; however, there may be many other causes such as a defective thermostat, water pump, low coolant, wrong pulley ratios, etc.
