Does My AC Really Affect Gas Mileage?

Does My AC Really Affect Gas Mileage?

How a Car AC works?

AC employs the use of a phenomenon which involves the use of pressure to change temperature. We will study this phenomenon further down the line while we study the overall working.

Car AC Parts

There are a lot of parts involved in making the air you share the car with comfortable. The parts needed are stated below.

  • AC Compressor
  • AC Condenser
  • Receiver Dryer
  • Expansion Valve
  • Evaporator

All of those work in tandem to push a fluid called refrigerant changing its state of matter to achieve the goal. Before we begin how they perform such a task we need to understand how they are placed with respect to the car and each other.


Opening the Windows vs Using the AC

I’m sure you might have heard something about keeping your windows open at higher speeds and in places like a highway is worse than keeping them close and using an AC. While that is true the conditions were it is worse are really limited and often not possible to achieve unless you are actively trying to do so. Below we will discuss some reasons for that and how this idea about an open window and the closed window came about.

Open windows might be worse

Car AC vs Mileage | Open windows
Car AC vs Mileage | Open windows

When a car is designed to be aerodynamic the consideration taken into factor is that the windows will be closed. These are the ideal conditions and the car is designed keeping this in mind. So what happens when you keep the windows open.

The air which was supposed to go through normally now faces two options, to go through unhindered from the outside or go inside the car through the open windows. We will now talk in brief about aerodynamics to help you explain why the air chooses the long way around instead of a shorter one.

What About Just Opening the Windows?

Turning your car into a sauna is never a smart idea. A miserable driver is a distracted, unsafe driver. But rolling down the windows and driving with them open reduces fuel efficiency even more than blasting the AC.

“Running the air conditioner when driving is actually more efficient and saves gas as compared to driving with the windows down,” Bennett says. “When the windows are up, the vehicle is more aerodynamic. When the windows are down, this creates excess drag on the vehicle, which increases resistance.”

Does turning off your AC make your car faster?

Yes, and you won’t. It doesn’t harm the car and provides a power boost. The AC was turned off automatically when the engine needed all of its power, thanks to a switch developed by automotive engineers.

Is it OK to leave AC on in car?

It’s not a great practice. But setting my environmental preferences aside, you can let any car idle with the AC on for a long time without doing any harm. As long as the cooling system is working properly, you should be able to sit in any modern car you buy and let it idle indefinitely.

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