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Leaving Ac On While Car Is Parked? Here’s What You Should Know

Leaving Ac On While Car Is Parked? Here’s What You Should Know

How long can I leave my AC running while the car is parked or the engine is off is a serious topic for discussion, and in this article, we will address it.

So, you’re in the parking area and waiting for someone. Maybe you’re early to the office and not in the mood to head to the office just yet or are finishing your pending work just to utilize this idle time.

Being the summer season, you’re uncomfortable sitting inside and decide to turn on the AC while the car’s engine is off, i.e., the car is parked. So, how long can I remain in such a position? Continue reading to know about this. 

Can you leave AC on while the car is parked?

There are two situations to take into consideration. First is the engine off, and second is the engine turned on.

It is because, as you know that the serpentine belt connects the compressor and engine. Now that the engine is off, the car will shift to using the battery (if there is a charge in the battery) to turn on the AC’s blower.

Hence, you’ll get air through the AC vents, but it will either give out fresh air or recirculate the air inside the car cabin.

However, if the engine is running and the car is parked somewhere, there is nothing to worry about. As the engine is in a running position, the compressor is working, and the AC will keep producing cold air.

So, if you’re not worried about emptying the gas tank of your car while it’s parked, keep the engine running, and AC turned on.

Never turn on the AC when the engine is off, as it consumes your battery to keep the AC running. If you are doing this, you will soon end up with a dead battery.

How long can you leave the AC on while the engine is not running?

If the car’s engine is not running and yet you propose to keep the AC on, how long this is possible will depend upon the charge left in the battery.

As the battery is responsible for keeping the various car elements up and running, the car has to keep other elements besides the AC.

Also, I said above, when the engine is not running, you’re not using the AC, and merely the AC blower is working out that, on average, consumes low fuel and power.

So, the battery charge will determine how long you can leave the AC on while the engine is not running. This period is in minutes, hours, or even the whole day. 

Will my car battery die if I leave the AC on?

It depends on whether your car battery is powering the air conditioning system of the car or not.

If it does, then yes, the car battery will die soon as AC consumes too much current from the battery. As the battery has limited capacity to run, it’ll soon run out of power and eventually die.

If the engine is running and all other electrical systems are working fine, then no, the car battery won’t die even if you keep the AC on for the entire day.

In the engine running condition, the AC system is using the fuel to run and produce cold air. Now, the amount of fuel left in the fuel tank will govern for how long the AC will keep going like that. 


How long can the car AC run without the engine varies depending on many factors.

Some of them are your engine capacity, battery capacity, and the charge left in the battery.

Whether your engine is on or off will determine the AC running hours if the car is parked.

Hence, if you’re not driving but still using the air conditioner, make sure it’s not powering through the battery, instead ignite the engine.

It will burden the fuel tank, and the fuel consumption rate will rise further. In another scenario, if the engine is not working, the car will use the battery to turn on the AC blower of AC.

Hence, you’ll get air through the AC vents, but it will either give fresh air (if the fresh air mode is on) or recirculate the air (if circulation mode is on) inside the car cabin.