Is It Ok To Leave Air Conditioner In Window During Winter? – All You Need to Know

| Last Updated: June 12, 2021

If you have an air conditioner in your window, it’s likely because you don’t have space for one elsewhere in your home. This also probably means that you don’t have space to store it during the winter.

So, can you just leave your air conditioner in the window during winter?

The answer, generally speaking, is yes. But, unsurprisingly, there are a few conditions for this. 

Photo credit:

Is it Bad to Leave an AC Unit in a Window During Winter?

So, what are these conditions? The main factor that will determine whether or not you can leave your air conditioner in your window is the style.

For example, one of the most common set-ups is a window air conditioner wedged into an open window. This is fine during the summer when an open window will be welcome. But, in the winter, cold air will be able to enter the room through the gaps on either side. 

Other potential damage can come from winter weather. Snow, ice, rain, and hail can all damage both the interior and exterior of your AC. 

Will Running AC in Cold Weather Damage It?

So, what will happen to the AC if left in the window during winter? If you live somewhere with relatively mild winters, then damage isn’t very likely.

But, if you live in an area where winter means lots of ice, wind, and snow, then your AC might become damaged.

There are two main factors that can potentially damage your AC in winter. These are low temperatures and water. 

Photo credit:

Water is the most obvious factor. Winter usually comes with a lot of rain, snow, and ice. All of which can damage the electrics of an AC. 

If your area gets cold enough for snow and ice, this can also cause damage. This can cause the coils to freeze up. This can sometimes be fixed. But with any kind of damage, frozen coils can cause permanent damage.

Cold weather can also cause the lubricant to thicken. The lubricant helps the air conditioner to run smoothly. If it becomes too thick, then it will slow down and potentially damage the air conditioner.

Will Cold Air Come in Through the Unit?

Even if you live somewhere with relatively low levels of rainfall, the cold can still be bad for your air conditioner. As you will likely already know, a window air conditioner works by drawing in air from the outside, cooling it, and pumping it into the room.

This means that your air conditioner has a series of slats and openings across its front and back. Unfortunately, even if you have a very securely locked up air conditioner, there’s a good chance that air will leak in.

Photo credit:

Will My Air Conditioner be Damaged if Left in the Window But Switched Off?

As the weather gets colder, you will want to stop using your air conditioner. But, leaving it switched off in the window can also cause damage. Even in colder months, mold can build up within the air conditioner. 

Dust and other small debris can also build up. This can usually be cleaned out. But, as you will know, dust can get into spaces that are often too small to clean. This can slow down your air conditioner and potentially cause damage.

How to Winterize a Window Air Conditioner

So, now that you know that it’s not the best idea to leave your air conditioner in the window. To help make sure that your AC doesn’t succumb to damage in winter, here’s our guide to winterizing your window air conditioner.

Photo credit:

How to Remove and Store Your Air Conditioner

If you can, the best way to winterize your air conditioner is simply to remove it. This will greatly reduce the risk of damage from the winter weather. It will also allow you to close your window to block out cold air. Here are some simple steps to removing and storing your AC.

1. Carefully remove and inspect the air conditioner

Once you have removed your AC from the window, you need to give it a once over. Check for any evidence of physical damage. Winter is the best time to repair your AC. This means you won’t have to worry about it breaking down in the middle of a hot night a few months later. 

2. Clean your air conditioner

This is a really important one. For anything in your home, it’s a good idea to clean it before storing it away. Wipe down the entire unit with a dry cloth. But remove the filter to clean separately. Wash the filter in warm soapy water.  

Depending on how complex your air conditioner is, you might be able to clean the inside as well. This is a good idea so just try to clean as much as you can.

Regularly cleaning your AC will keep it in good condition and make it last longer.

Photo credit:

3. Store your air conditioner

If you happen to have the original box, this will be the best way to store your AC. If not, try and store it inside another box or container. This will make it less likely for dust to fall on it and gather. 

It’s really important to store your AC in a dry place where it won’t be handled a lot. The best places will be in the attic or in a storage closet. It’s also really important to store the air conditioner upright. Otherwise, the compressor can become damaged. It will also cause the oil to move around rather than settle.

How to Insulate Your Air Conditioner

If you can’t remove your air conditioner from the window, then you can still protect it. Here’s a simple guide to insulating your air conditioner.

Photo credit:

1. Wrap the AC

You don’t need any special equipment to insulate your AC. The exterior needs to be wrapped to keep out the cold. You can easily use an old blanket or quilt. Make sure to cover the side panels as well.

If you have one, an AC cover can also work. But it will be a good idea to add extra insulation.

2. Seal the edges

Use strong tape to seal up the edges. This might not look great but you can make it look nice if you try. Make sure that the window is entirely sealed. Otherwise, cold air, rain, ice, or snow will push in.

Photo credit:


Overall, the best option is to remove your AC and store it somewhere dry for winter. This will keep your AC safe and your home warm. You do have other options to prevent your AC from damage. But these won’t be as effective as removing and storing the AC.

People Also Ask

Now you know the basics for keeping your AC from damage in the winter. But, there are still a few things that you might need to know. Here are just a few frequently asked questions that might be playing on your mind. 

Is It Bad To Leave the AC in the Window All Year?

The answer to this is yes and no. If you can, it’s best to remove your AC and store it away in winter. This will be the best option for preventing damage. If you can’t remove your AC, you will need to winterize it to prevent damage.

Can Air Conditioners Be Stored Outside in the Winter?

Not really. Air conditioners are warm weather machines. They can be badly damaged by winter weather conditions. If you can, store your AC somewhere warm and dry. This could be your attic or a storage closet.

When Is It Time To Winterize or Remove My AC From the Window?

It’s best to winterize or remove your AC when you are sure that you won’t need it again until next summer. This is the best option for preventing potential damage. Especially if you live somewhere prone to sudden drops in temperature.

Will an AC Cover Protect My Air Conditioner If I Leave It In the Window During Cold Weather?

Yes, to an extent. An AC cover should stop snow, ice, and rain from entering the AC and causing damage.

My name is Bob Wells and I am a retired HVAC tech from Washington state. I am currently retired and no longer do much with HVAC, however, I feel like I have a lot of knowledge in the subject and I wanted to create a website where I could talk about what I've learned and help upcoming HVAC techs. Find more info about me and HVAC Training 101.