Reduce voltage (14V to about 10V)

Hello together, I would like to reduce the voltage in a supply line for the cooler fan as easily and cost-effectively as possible.So the solution should pack a certain power and not smoke directly.The typical voltage converters (ideally with Poti) I find are either from the area of the microelectronics or then directly 12V to 230V for the cigarette lighter Thank you very much!