Can I Sleep In My Car With The AC Running? Here Is Why Its Dangerous

can i sleep in my car with the ac running

To specific individuals, like professional drivers, the car is not only a mode of transportation. It also acts like a mobile bed where they take naps. 

However, there are situations where laypersons may want to sleep but do not have any option but their cars. Those who have never slept in their cars are usually concerned about safety. 

Plus, some might be questioning if they are violating the driving rules. The car will offer you some comfort, but now it is safe to sleep in a car. Let’s explore the ins and outs of sleep in the car by answering the question. 

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Can I Sleep In My Car with the AC Running? 

Yes, however, the road experts highly discourage it. It’s because if your car’s mechanical functions aren’t up to standard, there are chances of leakage from its exhaust. 

Therefore the person snoozing could be at risk of suffocation because of reducing oxygen level inside the car.

Why it’s Dangerous

The major fume from the engine’s exhaust is carbon monoxide, plus other gases. Carbon monoxide is odorless and highly poisonous. The gas is deadly if it’s in closed spaces and large amounts. 

In such a situation, the carbon monoxide gas will replace oxygen in your blood, and this causes slow asphyxiation. If an individual inhales carbon monoxide in large quantities, it causes rapid death. 

It’s because the gas instantly removes oxygen from red blood cells. All the body cells need sufficient energy to function, and lack of it is undoubtedly detrimental. The contact of oxygen and carbon monoxide leads to the formation of carboxyhemoglobin. 

The carboxyhemoglobin makes the body cells useless, which affects the tissue’s functioning. It leads to a state that’s referred to as hypoxia. In this state, one experiences confusion, dizziness, and intense headache. 

If the person is awake and aware, they can escape death by simply getting out of the car. If one is asleep or intoxicated, they might not be mindful of the poison and silently die. 

However, most exhaust fumes do have a recognizable stench, but as mentioned, carbon monoxide gas is odorless. Therefore you may not know how much carbon monoxide gas you inhale in a closed space. 

One of the leading causes of such deaths in cars is malfunctioning AC. A malfunctioned, or old AC disrupts the air circulation system, and thus air does not replenish well. It will lead to a spike of harmful and toxic gases such as carbon dioxide and carbon monoxide. 

Additional Information 

The holes in the vehicle body (floorboard, trunks, etc.) allow harmful exhaust fumes into the passenger compartment. 

The gases are usually risky if the car is not in motion. Sleeping in a moving vehicle or a vehicle with an air conditioner on is safe. 

However, sitting in an idle car for an extended period is not advisable since exhaust fumes can still enter the vehicle. 

The symptoms of excessive carbon monoxide include confusion, headache, and nausea. The newest car models do come with fully-functioning ventilation systems. 

The systems cannot completely shut down, and it constantly pressures clean air into the cabin to eject the pollutants. The air intake is at the windshield base, reducing carbon monoxide accidents. 

The best way to avoid risking your life while in the car is by opening the window and putting on the air conditioner. 

Use CO Detector

If you occasionally sleep in your car, you should invest in a CO detector. There are several CO detectors explicitly made for vehicles.  

Is It Legal To Sleep In Your Car

It mostly depends on where you live, but sleeping in the car is illegal in most US cities. However, there are certain exceptions to this rule; there are rules about sleeping in your vehicle in Virginia and Florida. 

But the rules vary. The different cities make this illegal to reduce the number of homeless people loitering in certain places. The progressive and big towns also do not allow people to sleep in cars. 

In certain cities, rent can be high, and therefore, many people are homeless. The towns have built several homeless shelters to accommodate all that need them. 

If they catch you sleeping in a car, you will pay a fine of $1000 or get a six months jail time. However, most homeless people still sleep in their vehicles despite the strict measure. 

If the car has ineffective systems, this might lead to suffocation caused by Carbon monoxide. There are designated rest stops in other states or cities where drivers can stop their cars and take naps. 

However, you should always avoid private parking spaces and private property. Follow the laws by constantly observing the different designated times of parking zones. 

When it comes to sleeping in your car, the best thing to do is check the state’s or city’s laws to find out whether you will be violating them. 

Will Leaving The AC Running Damage Your Car Engine And Battery?

The health of your car engine and battery are equally as important. If the car’s AC runs for long, then your battery is at risk of damage. 

The engine can also overheat, damaging the radiator if it happens for an extended time without movement. 

The car fans are effective coolants only when the car is in motion, and the outside air also helps cool the car engine when the vehicle is in motion. The risk of overheating is higher when the car is in an enclosed space like a garage. 

Ideal Places To Park And Sleep In Your Car

The Walmart stores have some of the best parking spaces that you can sleep. Walmart offers overnight parking, which is well-lit, ensuring your safety. 

The stores are usually open for 24 hours, and thus you will have access to their restrooms at any time. 

The casinos are also a great place to park and sleep; they operate for 24 hours and have excellent security and cameras. It will be easier for the guards to detect any issues. 

If driving on a highway, the rest stops are the best and safest places to sleep or relax. Most rest stops have restrooms that operate for 24 hours, plus they are legal sleeping places in many states. 

Keeping Your Car Cool

There are several ways to keep your car cool while sleeping. The best and cheapest way to keep your car cool is by opening all the windows and doors wide open. 

The other common way is by using the air conditioner. You can also use the high-powered portable fan. The other easy and natural way is simply parking the car in the shade or using a windscreen sunshade. 

Further, you can cool your car using frozen water bottles such as ice packs. Plus, you can put tinted windows; they prevent UV rays from getting into the car. 

Keeping Your Car Warmer

To keep your car warm, you should invest in catalytic heaters. They are most preferred because they do not emit any carbon monoxide gas. 

However, they are not ideal for use when you are sleeping. It would help if you only used the heater to warm the car but unplug it when you want to sleep. 

The electric blanket is also another way of warming your car. You charge the blanket but remember to unplug it when you sleep.

Can I Leave My Car Running While I Sleep In It

Sleeping in your car is not only dangerous because of carbon monoxide poisoning; there are many other problems. 

By sleeping in your car, you risk being over-cooled by the AC, plus you can be a victim of sleep-related accidents too. 

The sleep-related accident happens when one is sleeping while driving and usually causes death or even injuries. 

However, you need to know that it’s much better to sleep in a motel or hotel room than to sleep in your car. 

How to Keep Safe

The best way to ensure you are safe is by carrying out regular maintenance on your car. Be taking your car to an enthusiast for checkups monthly or yearly. 

Always do this before long-distance journeys; the mechanic will be able to detect an AC blockage, damage, or clogged filters. If you have no other better option than sleeping in your car, ensure to take short breaks by getting out of the car often. 

If you sleep in a stationary car and the AC is on, it’s better to open the car window partially to allow proper air circulation. Overall, always avoid sleeping in your car as much as possible.


Sleeping in a car with the AC on is quite risky because of carbon monoxide poisoning. However, there are ways to help you ensure the air circulation is okay, like sleeping while the window is open or using the air conditioner. 

However, it’s inexpensive and safe to sleep in a cheap hotel room or motel than in your car while the AC is running. Plus, you will also get good sleep that’s more comfortable. 

If you have an electric car and it’s connected to a steady power source, then you can give it a try. However, remember that wear and tear also apply to such cars.