Can You Leave The AC On While The Car Is Parked And The Engine Is Running?

You’re parked, waiting for a friend or just taking a break. The weather outside is uncomfortably warm, and you’re debating whether to keep the AC running while you’re idling.

Indeed, it is possible to keep the AC on with the engine running when parked. However, to minimize fuel consumption, engine wear, and environmental impact, it is recommended to limit idling time. If parked for over 10 minutes, consider turning off the engine and AC, and seek alternative ways to maintain comfort and coolness in the parked car.

Now, let’s discuss the factors in deciding whether to keep the AC on in a parked car with the engine running.

Can You Leave The AC On While The Car Is Parked And The Engine Is Running?

When in a parked car with the engine running and the AC on, several things occur:

  • The engine is burning fuel to power the air conditioner.
  • The AC compressor is putting extra load on the engine.
  • The car is emitting greenhouse gases, contributing to climate change.

Though not illegal or dangerous, consider the impact on your vehicle and the environment when leaving the AC on.

Fuel Consumption

When the engine runs, it consumes fuel to maintain idle speed. Using the AC adds to the engine’s workload, increasing fuel consumption. This extra fuel usage can eventually affect your wallet.

To put it in perspective, consider the following table:

ConditionFuel Consumption (Gallons per Hour)
Engine idling, no AC0.1 to 0.3
Engine idling, AC on0.2 to 0.5

As you can see, running the AC while the engine is idling can almost double fuel consumption.

Engine Wear

The AC compressor puts an additional load on the engine, causing it to work harder. While modern engines are designed to handle this extra load, prolonged use can accelerate wear and tear. Furthermore, continuous idling with the AC on can cause the engine to overheat, especially in hot weather.

Environmental Impact

Leaving the AC on while the engine is running generates emissions, which contribute to climate change and air pollution. The EPA states that idling for 10 minutes produces around 1 pound of carbon dioxide. The added load from the AC increases these emissions.

Is It Safe To Leave A Child Or Pet In A Parked Car With The AC On?

While it’s tempting to leave a child or pet in a parked car with the AC running to keep them cool, this is not recommended.

This practice comes with several risks:

While it’s tempting to leave a child or pet in a parked car with the AC running to keep them cool, this is not recommended.

1. Engine mishaps: Picture this – you leave the car running with the AC on, but suddenly, the engine stalls or the AC stops working. The temperature inside the car can shoot up really quickly, and that could put your child or furry friend in danger of heatstroke. Not a fun scenario, right?

2. The invisible threat: Carbon monoxide can be a hidden danger. If your exhaust system has issues, it could leak this colorless, odorless gas into your car. It’s very unhealthy and you don’t want your loved ones at risk.

3. Security Concerns: It is an unpleasant thought, but leaving your car running with a child or pet inside may attract criminals looking to steal it. This could result in the potential kidnapping or injury of your loved ones. Adopting a “better safe than sorry” mindset is advisable in such situations.

How Long Can You Leave The AC On While The Car Is Parked And The Engine Is Running?

Usually, you can leave your car idling with the AC on as long as the engine’s fine and there’s enough fuel. The key factor here is the proper functioning of the engine compartment cooling fan(s) and other cooling system components.

But, keep in mind things like your car type, engine and AC condition, and outside temperature can affect this. Since every vehicle is different, you should consult your owner’s manual for guidance on idling with the AC on.

Though it’s handy to keep the AC on while parked, it’s best to cut down on idling time. Doing so can save fuel, reduce engine wear, and lessen your environmental impact.

Instead, consider turning off the engine and AC if you expect to be parked for more than 10 minutes, and explore alternative methods to keep cool and comfortable in your parked car.

How To Stay Cool In A Parked Car Without Running The AC

It’s clear that leaving the AC on while parked has its drawbacks, but how can you keep cool without it? Here are some practical tips to help you stay comfortable without relying on the AC:

1. Park in the shade: Choose a shaded spot whenever possible to keep the car cooler. This easy step can really change the inside temperature, so it’s comfier when you get back in your car.

2. Use a sunshade: Get a sunshade to keep out direct sunlight and lower the heat in your car. With various sizes and styles available, you’ll surely find one that suits your car and style.

3. Open the windows: Allow for natural ventilation by cracking the windows open. Keep in mind security and safety considerations while doing so. If you’re concerned about leaving your windows open, consider purchasing window vents, which can provide ventilation without compromising security.

4. Consider a solar-powered fan: These fans can be attached to your car window and use solar power to circulate air, helping keep the interior cooler without using fuel or battery power. Solar-powered fans are a green way to keep cool and cut down on AC use.

5. Stay hydrated: Drink water to regulate your body temp and feel comfy in the heat. Keep a reusable bottle in your car for a refreshing drink anytime.

6. Use a cooling towel: Cooling towels are made from special materials that retain water while remaining relatively dry to the touch. Just wet the towel, squeeze it, and put it around your neck or on your lap to cool down.

7. Dress for the heat: Wear lightweight, breathable clothing made from natural fibers like cotton or linen. Avoid dark colors, which can absorb heat and make you feel hotter.

8. Use your car’s built-in features to stay cool: Tinted windows can block some sun’s rays and keep the interior cooler. Also, cracking open a sunroof lets hot air escape, creating a chimney effect.


In short, leaving the AC on in a parked car with the engine running can lead to increased fuel consumption, engine wear, and environmental impacts. Instead, consider alternative methods to keep yourself, your passengers, and your car cool when parked. This choice benefits your wallet, your vehicle’s lifespan, and the environment.

Stay cool and stay responsible!

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