Is It Bad to Leave Car Idling With Ac on

Last Updated on May 13, 2023 by Ryan

Yes, it is bad to leave your car idling with the AC on. Doing so will waste fuel, increase air pollution and wear down parts of your vehicle faster than normal. Fuel efficiency decreases significantly when a car idles for more than 30 seconds; this means that you are wasting money by letting your car idle unnecessarily.

Additionally, exhaust from an idling engine contains high levels of pollutants such as nitrogen oxides and carbon monoxide which can contribute to smog and poor air quality in urban areas. Finally, leaving a car running for too long also causes extra strain on its engine oil, cooling system and other components which can lead to costly repairs over time. Therefore, it is best practice to turn off your engine whenever possible rather than leave it running with the AC on.

Leaving your car idling with the AC on can be a bad idea for two reasons: first, it is wasteful of fuel and second, it leads to unnecessary emissions. Idling your car with the AC running not only wastes fuel but also emits harmful pollutants into the air. It’s best to turn off your engine when you’re not driving or if you need to cool down before getting in the car, use an electric fan instead of keeping the AC on idle.

Should You Leave Your Car's Engine Idling? Myth Busted

Is It Bad to Let a Car Idle With Ac On?

It is not necessarily bad to let your car idle with the air conditioning on, but it can have a negative effect on fuel efficiency and engine performance. Idling with the AC running will put extra strain on your car’s engine which leads to more wear and tear over time. Additionally, idling for more than 10 seconds while using AC consumes more gasoline, meaning you’ll be spending more money at the pump in order to compensate for this added energy consumption.

Finally, leaving your vehicle idle for long periods of time can lead to increased emissions of carbon monoxide and other pollutants into the atmosphere. Therefore, if possible try to limit how often you allow your car to idle with AC turned on or off.

How Long Can a Car Idle With the Air Conditioner On?

It is generally safe to idle your car with the air conditioner on for up to 10 minutes. However, idling for too long can cause damage to engine components such as spark plugs and cylinders due to prolonged exposure to heat and moisture. To avoid this, it is best practice to limit idling time when running the air conditioner and instead turn off the engine if you plan on being stationary for more than 10 minutes.

Additionally, turning off your vehicle regularly will help keep its battery charged which can prevent a dead battery in case of an emergency.

Is It Bad to Leave Car Idling With Ac on


How Long Can I Idle My Car With Ac on

When idling your car with the AC on, you should generally not exceed 10 minutes at a time. After that amount of time, it is best to turn off your vehicle and allow it to cool down for a few minutes before continuing to idle. Doing this will help ensure that your engine does not overheat or suffer from any other kind of damage due to excessive idling.

Sitting in Car With Ac Running Carbon Monoxide

It is important to be aware of the dangers of sitting in a car with the air conditioner running while it is off. Carbon monoxide can build up inside the vehicle, creating an extremely hazardous environment for its occupants. Carbon monoxide is odorless and colorless, making it difficult to detect until symptoms like headaches and nausea appear.

To prevent carbon monoxide poisoning, drivers should always drive with their windows open or turn on their engine before turning on the AC system.

Is It Bad to Idle a Car Overnight

Idling a car overnight is generally not recommended, as it can lead to increased fuel consumption and unnecessary wear on the engine. Idling also produces emissions that are harmful to the environment and contributes to air pollution. It’s best practice to turn off your car when you’re done using it for long periods of time or if you’ll be away from it for more than a few minutes.


In conclusion, leaving your car idling with the AC on can be a costly mistake and may even damage your engine. Idling for extended periods of time can cause unnecessary wear and tear to your vehicle, resulting in expensive repair costs. It is better to turn off the engine and conserve fuel whenever possible.

Furthermore, it is important to make sure that you are aware of any local laws or regulations regarding idling vehicles before making any decisions about when or how long you should leave your car running. Taking these precautions will help ensure that you don’t suffer from unnecessary expenses due to idling.


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