How Long Can You Leave a Window Air Conditioner Running (24/7 OK?)

Your air conditioning unit is both a tool and an investment; getting the most out of it is essential for any homeowner. Knowing how to run your window AC unit properly is one way of doing this. But how long can you leave an air conditioner running? Read on to discover the answer.

Drawbacks of Leaving AC Units Running 24/7

Expensive electricity bills and more trips

While running your AC unit constantly may seem like a wise idea, this drives the cost of running window AC units up. Your air conditioner runs through multiple cycles an hour until it reaches a specific temperature. Turning it off for a few hours once it reaches the ideal temperature can save you money and energy.

Less efficient at dehumidifying

Air conditioning units are much more effective at dehumidifying when they are going at full speed. This typically only happens when the AC unit runs intermittently. Leaving your AC unit running at all hours will leave your home feeling muggier or more humid than it should, which is uncomfortable at the best of times.

Shortens lifespan

As with any machine, an AC unit’s parts experience wear with each use. Over time, the parts break or need to be replaced. By running your AC unit all the time, you are wearing the machine down much faster, shortening its expected lifespan.

Hurts the environment

Your machine uses hydrofluorocarbons, or HFCs, to bring down the air temperature outside before letting it into your home. If a 1.5-ton AC unit is left to run all day, it will use around 5344g of carbon. However, if you run the same unit for around eight hours a day, it will use only 222g of HFCs. Using your AC unit less can help decrease your impact on the environment.

Shouldn’t be left unattended

When your AC unit runs constantly, it runs the risk of causing an electricity spike. If an electricity spike happens, the compressor could become damaged or burned. This means potentially damaging other parts of your AC unit and posing a danger to yourself or your loved ones.

Leaving Window AC Running

So, How Long Can You Leave A Window Air Conditioner Running?

An air conditioning unit runs in regular cycles. These cycles are, briefly, as follows:

  1. .Hot and humid air is sucked in.
  2. .This air is cooled down via condensing on cold coils.
  3. .Cold air is vented back into the room.
  4. .Moisture from the air is either vented outside or put in a reservoir.
  5. .The compressor compresses the refrigerant on the condenser coils. The heat from this process is vented outside.
  6. .Repeat.

These cycles typically occur two to three times an hour and last between 10-20 minutes. When your machine finishes up a revolution, there is a spike in energy use. If experienced more than expected, this spike could cause your AC unit to short cycle or perform the incorrect number of cycles per hour. Short cycling can lead to electricity spikes, erratic temperatures, inefficient electricity use, and more.

So what is the best way to run an air conditioner? Every home, area, and air conditioning unit are different. The size of your home, your thermostat, number of family members, and unit size all play a role in how long you should run your air conditioning unit. Most people use automated settings on their units or run them for around 8-12 hours per day.

Why You Should Close Your Windows When Your AC is Running

  • Irregular and slow cooling Can you leave a window open with air conditioners running? Having your windows open while your air conditioner is on creates extra work for your unit. The added warm air and humidity make extra work during each cycle, resulting in irregular or slow cooling.
  • Forces cool air out When you open your windows while the AC unit is on, you create a vacuum that sucks all the cool air outside while letting warm air inside. Keeping indoor and outdoor air separate is key to having a cool and humidity-free home.
  • Unwanted dust Letting in the air from outside also brings in dust, pollen, and other airborne particles that get tangled in your air conditioner. As discussed in another article, mold spores feast upon organic matter like these and can thrive in your unit if not kept to a minimum.

Ways to Extend The Life of Your Window AC

Give your air conditioner a rest

Like with any machine or person, giving your air conditioning unit regular breaks ensures that it continues to work in top condition for an extended period. Letting it work in top condition allows your unit to cool your home and remove humidity properly without an issue.

Clean your AC unit on a regular basis (ducts and filters)

As we briefly mentioned above, your AC unit is susceptible to mold and dust. Keeping it clean internally and externally can keep those issues to a minimum and extend its overall lifespan. We recommend cleaning it thoroughly, paying particular attention to the ducts and filters, every couple of weeks.

Get regular AC tune-ups

Tuning up your AC unit in the spring before the big haul of summer can help prevent many long-term issues. By hiring a professional, you can keep on top of worn or broken parts, as well as other maintenance issues, avoiding any damage during the height of summer.

Allow air to circulate naturally

By leaving your windows closed during use, you allow the cool air created by your air conditioner to move naturally around the room or house. This cools your home at the correct and regular rate and allows your AC unit to work effectively for longer.

Check for water/refrigerant leaks

As part of your regular cleaning schedule, we recommend inspecting your machine for water or refrigerant leaks. Allowing leaks to continue can cause damage to your unit, your walls, or your floor that can have severe consequences if left unattended.

Check for Water or Refrigerant Leak

People Also Ask (FAQ)

Why does my window AC keep running even when it’s turned off?

There could be a variety of reasons for your AC unit to keep running. Some of the most common causes include short cycling or damage to various parts such as the thermostat, PCB assembly, and temperature sensor.

Why won’t my AC turn off when it reaches the set temperature?

It could be due to various reasons, including a dirty or frozen evaporator coil, clogged air filter, low refrigerant charge, faulty thermostat, a leak, or restrictive filtering system.

How long does it take for AC to drop 1 degree?

That depends on the size of your unit and home, as well as the power of the unit itself. Typically, a four-bedroom house can experience a one-degree temperature change in around three hours.

Is it better to leave the AC fan on or auto?

We recommend using the auto fan setting where possible. It is more energy efficient to do this rather than let it run continuously. Read the product description carefully, as not all units have an auto fan feature.

Do window air conditioners run out of freon?

The only time your window air conditioner would run out of freon or need a top-up is if the freon is leaking. You can pick more up at specialist stores or online if necessary.

Related Article Can You Recharge a Window AC?

Why does my window air conditioner sound like running water?

In most cases, your window air conditioner making sounds like running water indicate that the excess condensation drawn from the air is not draining correctly. We recommend inspecting your air-con and drip pan for leaks or overflow.


Can you run a window air conditioner 24/7? That depends on a variety of factors. We recommend considering your situation and running it in shifts. Performing preventative maintenance and annual tune-ups of your AC unit can help extend its lifespan and keep you cool for years to come.

Josh Mitchell

Josh Mitchell

My name is Josh and I am obsessed with DIY and improving my family home. HVAC topics can be tricky for homeowners so I decided to share my knowledge on the subject. When I am not working on DIY projects, you can find me at the beach or my local coffee shop.