Is It Bad To Have AC On With Windows Open In Car – 2023

To swiftly cool off on warm summer days, drivers frequently argue over whether to use the air conditioning (AC) while keeping the windows open. Discussions about the effects of this behavior, often known as “AC with windows open,” on energy usage, comfort levels, and fuel efficiency have been sparked.

Although running your air conditioner with the windows open is possible, it is not advised. When you run your air conditioner with the windows open, you risk damaging it and defeating the point of having it on in the first place.

Let’s examine the research behind this practice to see whether it harms the environment and your car.

Why Is It Bad To Have AC On With Windows Down?

It is not advised to run the air conditioning (AC) while driving with the windows open due to the negative impacts. Any cold air will leave the cabin if you open a window while your air conditioner is on.

While breathing in fresh air, the heat from the outside air will continue to heat the interior, making your air conditioner work harder to cool it down.

Why Is It Bad To Have AC On With Windows Down
source:glass doctor

Furthermore, operating the air conditioner with open windows might lead to dust buildup in your HVAC system, necessitating more frequent filter changes. However, if you must run the air conditioning and open a window, doing it once or twice will be fine. Avoid making it a regular occurrence to prevent long-term problems or harm. Your wallet will appreciate it as well.

What Happens When You Run AC With The Window Open?

Concerns concerning the effects on fuel economy, energy consumption, and the overall driving experience have been highlighted by the discussion over whether or not to use the AC while the windows are open. While the air conditioner is running, opening windows may cause external humidity to enter, increasing the moisture level within your house. It could feel stuffy and uncomfortable as a result.

1. Fuel Efficiency And Energy Consumption:

The car’s engine produces the energy needed to run the AC. The engine has to work harder to operate the compressor that cools the air when the AC is turned on. As a result, compared to driving with the windows down and the AC off, fuel efficiency may decrease.

Fuel Efficiency And Energy Consumption

2. Aerodynamic Drag And Open Windows:

To swiftly remove hot air from the automobile’s interior, windows should be opened while the AC is on. However, this method may have unforeseen consequences because of the increased aerodynamic drag.

The resistance produced by open windows at higher speeds may cancel out any efficiency improvements from the AC. Compared to driving with the air conditioner on and the windows shut, this can result in more fuel being used.

3. Comfort And Cooling Efficacy:

The draw of rolling down the windows is the prospect of quickly removing the car’s oppressive heat. However, this strategy’s efficacy might need to be revised.

Comfort And Cooling Efficacy

The AC must work harder to maintain the proper temperature because open windows enable the cold air it produces to escape. As a result, the cooling procedure can slow down, reducing comfort.

Additionally, if the windows are open, heated outside air can enter the car and negate the cooling effects of the AC. This phenomenon is more noticeable in heavy traffic or urban locations where the exterior air is not significantly colder than the interior.

What To Do when AC is on with Windows Open?

While running the air conditioner with the windows open could be alluring, there are a few things to remember to find the ideal balance between comfort and effectiveness.

1. Prioritize Windows Closed With AC:

Generally speaking, closing the windows when running the AC is advised for the best cooling and energy efficiency. This procedure guarantees that the cool air stays inside the car and that the AC system runs well without putting too much load on it.

Prioritize Windows Closed With AC

The higher drag caused by open windows typically outweighs the modest fuel efficiency losses associated with using the air conditioner.

2. Exceptional Situations:

Opening the windows before turning on the air conditioning may be advantageous in some circumstances. Allowing the hot air to escape before turning on the air conditioning helps hasten the initial cooling process if your automobile has been parked under the scorching sun for a considerable amount of time. Closing the windows will be more efficient in maintaining a reasonable temperature after the AC runs.

3. Temperature Considerations:

It’s important to determine the temperature difference between the interior of your car and the outside world. Keeping the windows open could not provide the intended cooling impact if the outside air is not noticeably cooler than the interior air. Relying on the AC with closed windows becomes the more practical choice in such circumstances.

Temperature Considerations
source:vehicle wisdom


1. When Should I Turn Off My AC And Open The Windows?

Turn off the air conditioner and open the windows once the weather cools: If you reside in a cooler, northern location where late summer outdoor temperatures often range between 70 degrees and less in the evenings, you may benefit from doing so as long as the humidity is low.

2. Is It Bad To Sit In My Car With It On?

Sitting in an idle vehicle exposes you to more of the car’s interior’s polluted exhaust. The harm to your health is not worth the warmth you might feel from a car heater. Exiting your automobile when it is parked and waiting and entering a business or store is healthier.

3. Does AC Burn Car Gas Or Windows Down?

More so than driving with open windows, air conditioning decreased the miles per gallon in both vehicles. In an experiment conducted by the television program Mythbusters with two identical SUVs on a test track, the SUV with the windows down covered an additional 15 miles before running out of gasoline at 45 mph.

4. Does Driving Without AC Save Gas?

As opposed to driving with the windows down, Bennett claims that using the air conditioner is more fuel-efficient. “The car is more aerodynamic with the windows down. When the windows are open, the car experiences more drag, which raises resistance.


The final choice in the ongoing discussion regarding operating the air conditioner with the windows open should be made depending on the situation, traffic situation, and personal comfort preferences. While there may be slight reductions in fuel economy, it’s important to keep the temperature stable and ensure the AC operates effectively. You may have a comfortable ride without sacrificing energy economy by putting the most efficient cooling method first.

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