Does it cost oil to turn on the warm air in winter? What principle?

Of course, it costs oil to turn on warm air in winter for the simple reason. The heat of hot air comes from engine coolant, not exhaust heat. The heat of the coolant is finally generated by the combustion of gasoline. The normal working water temperature of modern engines is generally kept at 90 degrees. If there is no extra energy (gasoline combustion), the working temperature of the engine will continue to drop with the work done by warm air. In order to maintain a reasonable working water temperature, the computer will make a judgment and increase the oil supply (water temperature is also one of the basis for the size of fuel injection! ), then the fuel consumption will increase unconsciously.