How Long Can an AC Run Continuously? [Or Per Day?]

Nothing beats a good air conditioner on a dog day. We can’t live without cool air, but we’re also concerned about whether or not our air conditioners can run continuously or for how long. 

Luckily, air conditioners are designed to work 24/7. It will not cause any damage if you use it 24 hours a day. However, you don’t have to do so because it will lead to high electricity bills, a shorter lifespan, and more maintenance.

You should adjust the running time based on your specific situation. 

In this post, I will explain why running an AC continuously is generally safe, but it may not be the best option for you. This information could be extremely beneficial to you, so keep reading!

Is it OK for an AC to run continuously?

Air conditioning units, including central air, window AC, split AC, and portable AC, are designed to work continuously. You shouldn’t be concerned if you forget to turn off your machine before leaving for work. It is not likely to catch fire or cause water damage. 

Many people worry about the compressor overheating due to the continuous working.

First, models these days will turn off automatically or even trip the breaker when the compressor is overheated as a failsafe. 

Second, the compressor will not always operate at maximum capacity.

If you have a non-inverter, it will turn off when the room cools to the set temperature and then turn back on when the temperature rises.

If you have an inverter model, it will work at a low speed when the room is already cool. 

In either case, the compressor and the fan will have time to take a break and will not be susceptible to overheating. 

As a result, we can deduce that running an AC continuously is generally OK.

However, you should make sure your machine is in tip-top shape before doing that. If it is making a buzzing noise or keeps turning on and off, it could be a sign that there is something wrong, and you should get it fixed before running it again. 

How many hours should an AC run per day?

While you can run your AC for up to 24 hours per day, it doesn’t mean that you should do so. My advice is that you should decide how many hours to leave your AC on according to a few factors listed below. 8 hours is a good choice for most households.

Indoor temperature

Usually, it is recommended to turn on your AC when the indoor temperature is above 75 degrees.

The higher the temperature, the longer it will take for an AC to cool a room. In addition to that, it often means you need to run your machine longer to keep the room cool. Otherwise, the hot air outside will seep into your house gradually.

However, since the temperature will fall at night, you don’t need to run it 24/7 in many cases. 

Typically, running an AC for about 8 hours a day is adequate for most families if the high is not over 100s and the low is not over 85s. 

Your daily activities

How much time you spend in the house also plays an important role. As an AC consumes much more electricity when actively running, you’d better leave it on when you just leave for one or two hours. However, for those who have a typical 9 to 5 job, turning it off during the day is your best bet.

Do you have pets at home?

pets need air conditioner

Like our human beings, our furry friends will not feel comfortable when staying in a hot room. They may also get sick because of it. 

As a result, you must increase the running time of your air conditioner unit to accommodate them.

Cons of running an AC continuously

Sometimes, you have to or like to run an AC for a long time. Of course, you will enjoy the bliss of comfortable temperatures all the time during the hot summer months, but there are some possible disadvantages of doing so you should be aware of.

High power consumption

Only if you can cool your room continuously without paying high energy bills, however, as you already know, the plan won’t work. 

Even if you have a dual inverter model, it will cost a significant amount of energy when the running time is long. 

The high power consumption could not only allow you to feel the pinch of your finance but also do harm to the environment. 

Reduced lifespan 

Although leaving an AC on will not result in any serious damage, it will cause more mechanical tear and wear, reducing the lifespan of your machine.

If you are not in a position to replace your air conditioning system every five years, allowing your AC to take a break every so often is a better choice. 

More cost and time on maintenance

To some extent, air conditioners can improve indoor air quality. This is due to the fact that the air filter can filter out a part of dust and dirt in the air. Over time, those contaminants will also accumulate in the evaporator coil and condenser coil. 

If you continue to run your AC, the filter and coils will get clogged sooner. In other words, you should clean them more frequently. Don’t ignore this issue because it will affect efficiency and result in more problems. 

On top of it, due to the tear and wear mentioned above, you can expect to pay more on replacements, if not repair bills, if you have the related expertise. 

Sum up

Don’t be alarmed if you leave your air conditioner on all day. It is generally safe to leave your air conditioner on for up to 24 hours.

However, you should decide how many hours to run your AC per day based on the indoor temperature, your schedule, and whether or not you have pets. There is no single definitive answer to this question. If the weather isn’t too hot, 8 hours should suffice.

If you have to run it continuously, expect higher power bills, a shorter lifespan, and more cleaning and maintenance.

Check out the two posts below if you have a portable or window unit:

Can you leave a portable air conditioner on all day?

How long can you leave a window AC running?

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Liz Yang is the founder of Airsmartly. She has been working at home for a few years and realizes that the performance of the HVAC system plays such an important role in our life. She has tested a lot of products in person, like humidifiers, air purifiers, dehumidifiers, and ACs, and wants to share tips about using or troubleshooting these products with you. Her uncle is an HVAC expert with over 30 years of experience in the field, and often offers assistance when she is unsure how to handle a situation. He is also in charge of reviewing the articles on this site.