Is It Safe to Leave Window Air Conditioner on All Day?

Do you want to know if leaving the window air conditioner on all day is safe? Of course, forgetting to turn on the air conditioner before leaving the house is a possibility, but what about leaving it on all day? Even though air conditioners are designed to last a long time, there are excellent reasons to turn them off for part of the day.

In general, it is safe to leave the window air conditioner on all day because every system is built to withstand a lot of usage. But it might not be the best due to higher electricity bills, durability and lifespan of the system, and environmental factors.

If you are unsure if your window air conditioner can be left on all day and want professional advice, you can get assistance here.

How many hours should a window AC run per day?


A window air conditioner is meant to cool down only a room in the house. Since it is a smaller unit than the one required to cool the entire home, it needs to run a little longer to lower the temperature in a room.

In general, a window AC should run for 12 hours to keep the environment comfortable, but the length of time required for AC to run can change based on the weather and climate of the area, the house insulation, the air conditioner power, and efficiency.

In addition, not all the window AC units have the same size and can be more potent than others. So depending on the efficiency of your unit, you could lower or increase the running time.

Is it okay for an air conditioner to run continuously?

In general, air conditioners should only be used when absolutely necessary. Even if your air conditioner runs all day, it cannot guarantee that your room will reach the correct temperature.

The air conditioner might be more effective if you set the thermostat and let the unit run only when required to maintain the temperature and not more. Running the air conditioner all day will only work to increase the electricity bill.

In addition, it can overwork the system leading to damage faster or even breakdown. But, if you have to run your system all day to get cool air, it can signify that you have a problem with your air conditioner, and you should determine if there is a malfunction somewhere.

Can I leave my window AC on when I’m not home?


You can leave your window AC on when you are not at home. However, you should set up the temperature you want your house to have when you are not there. In this way, the system can run only for the necessary time to keep your home comfortable without running continuously.

In some circumstances, leaving the air conditioning on can be preferable to constantly turning it on and off; the thermostat can ensure that the space is only cooled when the temperature rises.

What to consider when deciding how long the air conditioner should run

Consider different factors if you are trying to establish how long your AC unit should run to cool your house or room. For example:

  • Size of the AC unit
  • Climate
  • Level of the house insulation
  • Air conditioner efficiency

When installing the air conditioner and deciding which one to choose, it is necessary to calculate the size (square feet) of the area you need to cool. In this way, it is possible to estimate how long the air conditioner needs to run to cover the required space.

If you live in a hot climate or if it is hot for a substantial portion of the year, you will need to use your air conditioning system more frequently. In a cooler climate, you can use the air conditioner for only a few hours per day (4-6), rather than 12 or more.

The insulation level of the house is another crucial factor that can influence how long you should let your AC run.

A properly insulated house can keep cool air in each room longer by preventing it from leaving the house and blocking the hot temperature outside the house from affecting the inside of the house.

The air conditioner’s efficiency can affect how long you have to keep the unit running. If something compromises the efficiency, for example, dirty filters, the unit has to work harder and longer to reach the temperature set by the thermostat.

How can I save on energy costs when using my AC unit?


If you operate your air conditioner for several hours each day, you will almost certainly wind up with a big power bill at the end of the month. Here are a few tips that can help you cut cost on your utility bills.:

  • Change filters often to increase efficiency
  • Proper insulation of the house
  • Make sure to use a programmable thermostat to save energy
  • Keep at minimum indoor heat-production activities (oven usage, etc.)
  • Run the AC unit only when it is necessary
  • Get an appropriately sized AC unit.

Regular maintenance can help keep the AC unit efficiency high, so you do not need to run it longer than needed. Simple things such as regular cleaning, changing the filters, and testing the thermostat can get your system in shape for higher performance.

Yearly maintenance done by professionals can add that extra level of security and prevent earlier breakdowns.


In general, it is safe to run a window air conditioner all day, but it is not advisable and, in some cases, not even necessary if the AC unit is working well. Air conditioner systems are durable and can run all day for weeks without experiencing any problems.

But a few changes in the setup of your AC unit and the house will allow you to run the AC for a shorter time. If you are not sure about your system, do not hesitate to contact us for assistance and professional help.

Back to top button