AC Buttons In Car: Settings & Meanings Explained

If you’re anything like me, you’ve stared long and hard at the “re-circulation” and “fresh air” buttons in your car without really know when to use them. Given enough thought, however, most of can gather from context clues alone what each button does, but the part that remains unclear is exactly what each one is good for.

In short, the “re-circulation” mode takes air from inside the vehicle and re-circulates it through your car’s AC system to help reduce the time it takes to cool your vehicle down. The “fresh air” mode pulls fresh air in from the outside of the vehicle, which is then ran through your AC system, and blown into your car. Both modes will keep your vehicle cool but the “re-circulation” mode will do it more efficiently as its much easier to reduce the temperature of air that’s already been cooled down once.

In this article we’re going to discuss the meaning behind all of your car air conditioner buttons so you can know when exactly you should be using them as well as giving you some tips on how to keep your car cool this summer. Keep reading to learn more!

Which Air Conditioning Setting Should I Use?

Re-circulation Mode

Re-circulation mode is best used during the warmer months where cooling your vehicle down quickly is a must. No body, including myself, wants to wait any longer than we have to for our vehicle to cool down when its 100 degrees outside and you’re already sweating bullets!

As mentioned earlier, the re-circulation mode works by taking the air inside of your vehicle and running it back through your AC system. It works a lot like the AC in your home. If you have a heat pump, it continuously circulates the air that’s already in your house through the cooling system and keeps your house nice and cool. It would be totally inefficient to constantly pull in and process new, warm air when you already have cool air to work with. The principle is the same with your car’s AC.

It’s also much easier on your vehicles AC system to re-circulate cool air than to cool down fresh air. Use your AC buttons wisely. Your AC system will thank you!

Fresh Air Mode

Typically fresh air mode is best utilized during the winter months or whenever defrost is being used to clear foggy windows. The reason for this is that relative humidity drops whenever air is heated (using heat or defrost) and using the re-circulation mode doesn’t help to remove humidity. By adding fresh, outside air to the interior of your car, you can more closely match the humidity level inside your car to that outside which will help defog your windows faster. Anytime your car is fogged up for any reason, its best to use fresh air mode.

Also when attempting to defog your vehicle, with hot or cold air, its best to turn your vehicles AC button on. This button does more than activate your vehicles AC system, it also helps pull humidity from the air which will help defog your vehicle more quickly. If attempting to defog in the winter, simply turn the heat on full blast, turn the AC button on, and select defrost mode. This is the fastest way to defog your car.

Fresh air mode is also used during the summer. When you first get into your vehicle, extracting the hot air quickly is a must. By using the fresh air setting, you are forcing cooler outside air into your vehicle. Once the vehicle starts to cool off, its best to switch over to re-circulation mode to make the cooling process faster.

What Exactly Does the AC Button Do?

Most of us, including myself, have just assumed the AC button is to only be used during the summer. And we would all be wrong. The AC button is meant to be used during summer and winter months. So regardless of if your trying to heat or cool your car, its perfectly safe to use the AC button.

When the AC button is activated in conjunction with cool air, it forces air to pass through a compressor and condenser which helps cool the air and remove any excess humidity. This also helps keep your windows from fogging up. When you use your car AC with heat, the air passes through the compressor and over the heater core which results in dry, hot air. Exactly what you need when trying to defog or defrost your vehicle.

To put it simply, the AC button activates the air conditioning system and forces air, whether cold or hot, through a compressor which removes excess moisture/humidity and provides dryer air to your vehicle, resulting in less humidity.

AC button in car.

What About the Max AC Button?

What the max AC button does is simply turn on the AC and the re-circulation mode at the same time. When you press the Max AC button, it activates the AC and the re-circulation mode and in some vehicles, forces all air through the dash vents to help cool the vehicle as quickly as possible.

It basically allows you to do two, sometimes three things in the click of a single button. Its more of a convenience feature than anything but it is nice to have.

Other Things You Should Know

  • One thing to mention is the popular misconception that claims running your vehicle on re-circulation mode will deplete the vehicle of fresh oxygen and make its occupants drowsy and groggy. This simply isn’t true. Your car will constantly take on new, fresh air in small amounts even if your AC mode isn’t set to fresh air. So no, you’re not going to pass out due to oxygen depletion if you refuse to change your AC settings.
  • Something to be aware of when using fresh air mode is that any exterior smells will be sucked right in through your AC and blown into the car. This means exhaust fumes and smells from other vehicles, and the stench of roadkill will be smelled a lot stronger than it would be if using re-circulation mode. Re-circulation mode doesn’t make your vehicle immune to these smells but it does cut down on how strong they are.
  • Not all vehicles have a re-circulation button. Many newer vehicles are equipped with technology that automatically turns the re-circulation on or off. This takes all the guesswork out of trying to figure out which mode you should use and when. So there’s no need to worry if you don’t see a re-circulation button in your vehicle.

A Quick Summary

Re-circulation Mode:

  • Re-circulates air already in car
  • Cools vehicle quicker
  • Easier on AC system
  • Best used in summer months
  • Will not deplete the oxygen in your car

Fresh Air Mode:

  • Pulls in air from outside of vehicle
  • Best used first to cool down vehicle
  • Best for defogging vehicle windows
  • Outside smells are stronger

Tips for Keeping Your Car Cool This Summer

Now that you know how to use your car air conditioning settings to your advantage, here’s a few tips for keeping your car as cool as possible this summer.

  • Keep the freon level in your car topped off. A car that’s leaking or low on freon will not cool your vehicle very well. Keep your AC in shape by regularly checking the refrigerant level in your car and getting it serviced on a consistent basis.
  • Keep your windows cracked in the summer to help trapped heat escape. Make sure not to leave them down too far. The last thing you want is for someone to be able to reach in and unlock your doors. If you’re concerned about it raining and getting the interior of your car wet, you can always buy a set of rain guards.
  • Buy a heat ventilation fan. These fans are great for removing hot air from your vehicle and forcing in fresh, cooler air. They won’t keep your car icy cool by any means but they will help in reducing the amount of time it takes for your AC to bring the temperature down.
  • Keep a windshield sun shade in your vehicle when not in use. I personally prefer the retractable ones. They are super easy to set up and once installed it only takes one hand to operate them. Having one of these in place can drastically reduce the interior temperature of your car while also blocking out harmful UV rays.
  • Make sure you run your AC on fresh air mode when first starting your vehicle then switch over to Max AC to cut down on the time it takes to cool your vehicle.
  • Park in shaded areas if possible. If this is not an option, believe it or not, they make whole car umbrellas which provide your car with the shade it needs to keep it relatively cool. I should also note that car covers block UV rays as well.

There are many other car accessories for hot weather that will help keep your car cool during the summer months. Here, you will find a bunch of products designed specifically for keeping your car cool in the blistering heat.