Is It OK to Start Car With AC on? How does car air conditioner work?

Is It OK to Start Car With AC on? How does car air conditioner work?

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There is nothing as soothing as blasting the air conditioning system in your car on a hot afternoon.

The main purpose why it is installed in the car is to cool its passengers and make your ride comfortable.

However most cases we fail to take maintain and take care of the ac or even ask some of the important questions until the air conditioner stops working.

That’s when one starts wondering how does car air conditioner work, how can  I fix the ac unit, Is it OK to start car with AC on etc.

I don’t think there is any modern car that does not have the AC system installed in it.

Unlike what most people think, the AC in your car does not create its own cold air, all it does is make the air that is already in the car cooling system.

And that is why in post we will look at what the air conditioner symbols mean in a car when is shows up.

How you can circulate the air in your car, so if any of the following questions bothered you, and then stick around to the end of this article:

  • how does car air conditioner work
  • Is it OK to start car with AC on
  • What do the air conditioner symbols mean in a car
  • How do I circulate the air in my car

Related Article: 5 Reasons why Car is Overheating When Air Conditioner Is On

How does car air conditioner work

Is It OK to Start Car With AC on? How does car air conditioner work?

The components that build up the automotive air conditioner system are the compressor, condenser, evaporator, receiver, expansion valve, and refrigerant.

A car AC uses all these components to cool the air inside the car. First, the compressor turns the refrigerant into a liquid form by compressing it.

The liquid will then flows through different tubes that are in the condenser.

With this, the refrigerant liquid will come in contact with any air coming from outside the car.

After this, the refrigerant will enter the receiver, and then whatever moisture left in the refrigerant will be eliminated by a desiccant.

This process will create a cooler refrigerant and also maintain the system.

After that, the refrigerant that is now cool will enter the expansion valve. The refrigerant will move to the evaporator easily now as there will be a reduction of fluid pressure.

The refrigerant will now pass through the evaporator. Any air that is coming from the passenger’s compartment will enter the evaporator and escape through its core.

The air coming out of the evaporator now is cool and the fan will blow it from the vents thereby cooling the car.  That is how the AC system in a car works.

Is it OK to start car with AC on?

Every car owner has different things that worry them about the maintenance of the car. One of such thing is whether it is okay to start the car with the air conditioner still on. Well, the simple answer is NO! There is nothing harmful about starting your car while the AC is on. Although there are so many actions that might affect your car negatively, this is not one of them.

What you need to know is that the operations of the car’s system are different. When the engine of the car is off, the vehicle will automatically shut off its power.

This means that as you are starting the engine of the car, every component like AC, radio, and so on will get shut off automatically.

It does not matter whether they are on or not. Doing this may enable the needed current to move from the car’s battery to the starter motor.

Immediately the car begins to operate, the components gain power and they start working where you left them.

In addition to that, the AC system was designed in a way that it has to come on suddenly. Therefore, even if the system is coming on when you start the car, it is just like you are putting the system on automatically.

So, it is okay if you start the car with the AC on and it will not affect the engine of your car in any way.

It does not matter whether the AC is on or off before you start your vehicle’s engine.

What do the air conditioner symbols mean in a car?

The air conditioner symbol of a car has two buttons which do different things. The first one is the recirculation button and the second one is the fresh air mode button.

So many vehicle owners do not know the difference between these two buttons and when they can be used.

Recirculation mode

If you want to circulate the air in the vehicle, then this is what you will use. Once you press it, the air duct that is at the front of the vehicle will close. This will stop the flow of air from outside the vehicle.

There are different reasons why a person might want to use this button. If you are driving behind a truck and you do not want unpleasant air to come into the car, you can click on this button.

The recirculation button can help to protect against dirty air from getting inside the car. In addition to that, if you want the AC to want very fast, you can also use this button.

If you are just getting into the car from under the hot sun and you feel like the AC is taking too much time to circulate, then this button is the best option for you. It is very efficient and stronger than the fresh air mode.

Fresh air mode

The second symbol on the AC system is the fresh air mode. You can select this button if you have a foggy windscreen and you want to get rid of it.

The cause of foggy windscreen is due to the difference in the car’s external and internal temperature.

To defog your windscreen, just click on the windscreen defogger in this mode and the outside air will blow to the window.

You can also use the AC to defog once you notice the front window is cloudy. Furthermore, the fresh air mode is useful to ventilate the car.

 If you ate something with an unpleasant odor or smoked inside the car, you can use it to bring in the fresh air. It will open the air duct and bring in fresh air into the car.

How do I circulate the air in my car?

Just like I have mentioned above, if you want to circulate air in your car, you will have to use the recirculation button.

When you press the recirculation mode, it makes the air circulate much faster and efficiently.

Imagine just getting inside the vehicle after spending sometime under the sun, it is the recirculation mode that will quickly blast the cool air to every part of the car’s exterior to make environment conducive.


This post explained some of the functionality of an automotive air conditioner and answers your concerns Is it OK to start car with AC on? 

We also looked at what do the air conditioner symbols mean in a car. The AC is one of the systems of a car that gives both driver and passenger the utmost comfort. It provides the circulation of cool air and makes you enjoy the car ride.

I hope this post helps you, please share if it did.

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