What happens when you open a window when the air conditioner is running?

When it is hot, you want to cool down your room as soon as possible. Some people open the window while the AC is running to speed things up. Do you think opening a window when the air conditioner is running will make the room cooler? Then you must know that it is a big misconception you have.

Your AC will run but it won’t be able to cool your room down. The hot air from outside is able to overpower your AC and this results in a hotter room. You should keep all the windows of a room closed when its air-conditioner is running. 


The following happens when you open a window when the air conditioner is running:

Advantages of keeping your window closed

Hotter room

If you want to refresh the air in your room, open the window but switch off the AC. But if you open your window on a hot day, the air will quickly become hot. And it will heat your room too. As a result, when you turn your air conditioner back on, it will have to work much harder to make your room cold.

An AC will also work less efficiently if you keep it on while a window is open. This can lead to your AC wearing out quickly and start malfunctioning. Then you would have to bear the cost of replacing it.  This can also affect the humidity percentage, leading to an uncomfortable room.

Your AC will have to be turned on at a higher setting when cool air is continuously allowed to flow out. Therefore, you will automatically make your air-conditioner work harder. You will also make it run longer. The AC unit will not get adequate time to rest. Most electrical appliances’ life span diminishes because of high strain, and your AC is no different. Furthermore, keeping windows close will also get you lower power bills. 

Uneven cooling

When you open a window when the air conditioner is running, there will be different temperatures within your house. This problem will be enhanced if the thermostat is close to the window as it won’t be able to get a reliable measurement of the temperature in your house. The HVAC system will struggle to create a comfortable situation in your house.

Consumption of more electricity

If you open a window, the thermostat will no longer be sensitized to the correct temperature. Thus, even if you want to, the air-conditioner will not shut off. The frequent cycling of your air-conditioning will hike up your power bill. This is because the unit will keep running continuously.

Dusty home

If you open up your window, dust can get inside. This dust can build up around your AC.

This will eventually lead to the breakdown of your AC and again lead to higher electricity bills. When the evaporator coil gets dusty, it hinders the cooling process. When dirt enters the filters, the air cannot flow properly through the handler. As a result, the AC cycle will last longer. Furthermore, when the evaporator coil and the air filter get filled with dirt, the compressor can get fried and the coil becomes frozen. 

You can avoid this situation by cleaning your AC from time to time.

More humidity

When you open a window and run your AC too, your home is bound to get more humid. The humidity will keep increasing till you close your window. An AC not only cools down a room but also eliminates humidity. Thus, when you open a window when the air conditioner is running, it will have to work twice as much to eliminate the moisture. This can lead to mold and other problems. A dehumidifier can help with removing humidity from the air.

You can get a moisture meter to make sure that your room has the right humidity levels.

Pushing cool air out

Your AC will not function to its best capacity even if you slightly open the window. The air from outside can push the cold air, that comes out of the AC, away. Also, the cool air will be forced to blow out of the window. 

It can be a great idea to open a window to get some fresh air but you should turn your AC off when you do this. Once the room has been refreshed, you can turn the AC back on. This makes sure that you get the most out of your HVAC system. Opening your window once a day is often recommended. Your room will get more fresh air if you open multiple windows at the same time as the draft that this creates pushes out the old air.

Can you keep a window open at night when you have AC?

You can but should not. Many people who live in warm climates, like to open the windows at night and switch off their ACs. They like the fresh outside air to flow in before it starts getting hotter in the morning. But they are either not aware of or forget about the after-effects of this action. The air at night usually has a higher humidity level. This means their home becomes more humid too. This can cause mold.

Most portable AC systems come with a seal to close the window after you have installed the drain. This keeps the hot air outside.

By the time you wake up, the air might be hotter again as well. This pushes your AC to work harder.

Next to keeping the window closed, there are other things that you can do to keep your room cool. This ranges from covering your window to painting the outside wall in a light color.

To conclude, we can state that you shouldn’t open your window when your AC is on. When you leave the windows open for the entire night, you allow a lot of moisture to enter your home. By doing so, you are adding to the workload of your air-conditioner. When you switch on the AC in the morning, you will have to work extra hard to get rid of the excess moisture. The humidity makes a room warmer, so it also will work harder to cool your room. As a result, you will need to keep your AC running for a longer time than usual.