Should I Cover My Window Air Conditioner In The Winter?

Window air conditions are an effective and efficient cooling solution, especially for those who are looking for supplemental AC when the weather gets warm. You can learn all about the advantages of installing a window unit in our guide to window air conditioners.

After purchasing and installing your window air conditioner, regular maintenance is important if you want the best performance possible. One of the most overlooked aspects of window AC maintenance is keeping it protected from the elements, and failing to do this can not only downgrade the unit’s cooling performance but ruin it entirely.In this guide, we’ll tell you whether or not covering window air conditioners in the winter is necessary, as well as the steps on how to insulate a window air conditioner for the winter season.

Why Should You Cover Your Window Air Conditioner in the Winter?

In order to better understand the importance of investing in a window AC cover for winter, it helps to know how window ACs work. This type of unit is installed within a window frame and works by drawing hot air from the surrounding area, cooling it down with the help of an internal compressor, then expelling the cool air back into the room.

During this process, there is still some hot air leftover, and this is expelled outside through the back of the unit. That means that a good portion of your window AC is completely exposed to the elements, and that is why it’s important to add protection – especially when the temperature drops outside.

Here are the main reasons why you should cover your window air conditioner in the winter:

  1. .To keep it protected from dirt and debris
  2. .To keep it protected from frost and snow
  3. .To keep it protected from dripping water
  4. .To keep it protected from rodents and insects
Cover Window AC During Winter

What to Consider When Choosing a Window AC Cover

There are many products on the market that are specifically geared towards protecting and covering a window AC unit from the outdoor elements. When deciding on a window AC unit cover for winter, these are the main considerations to factor into the buying process:

  • Material Quality:
    The entire point of investing in a window AC cover is to protect the unit, so you’ll need to choose a cover that’s constructed from durable material. Most outdoor covers are made from harder materials that are capable of standing up to the elements, like derivatives of plastic or polyethylene.
  • Cover Size vs. AC Size:
    Before you purchase insulated window air conditioner covers for winter, always check the unit’s dimensions. Take exact measurements of the AC’s depth, length, and width so that you can choose a cover that will fit the unit. Some covers are labeled as one-size-fits-all and come with adjustable straps or drawstrings.
  • Reliability & Weatherproofing:
    If you can’t count on your cover to protect your unit when the temperature drops and snow starts falling, you might as well not have one at all. You should be able to rely on the cover to protect against wind, rain, cold temperatures, rust, debris, and more.
  • Aesthetics:
    The way the cover looks isn’t considered as important as the way it protects, but it’s still something to think about. Remember, this cover will be visible from the outside of the house, so try to choose one that blends in with your home’s exterior.

Related Article Will Rain Damage a Window AC?

Choosing a Window AC Cover

How to Cover & Insulate Your Window AC for Winter

There are 3 different options for protecting a window AC for the winter:

1. Weatherizing the AC Unit

If you don’t want to buy a window AC cover for the winter, you should at the very least weatherize the AC. To do this, remove the outside cover of the window unit, exposing the internal components.

Using a large plastic garbage bag, place it over the unit so that you cover the entire outside frame. Tuck any excess plastic inside the unit so that everything is nice and sealed, and use duct tape to hold the bag in place if necessary. Then, reinstall the outside cover.

2. Insulating the AC Unit

Investing in the best window insulation is another solid option for wintertime protection. For this, you’ll need firm foam insulation cut down into strips that fit along the sides of the unit.

You can use a putty knife to push the insulation into the gaps between the unit and the window frame. Spray insulation is another option, but just know that it expands dramatically, so a little goes a long way.

Insulating a Window AC

3. Covering the AC Unit

It’s easy to find durable covers for a variety of window unit shapes and sizes. When using a cover, just slide it over the outside portion of the unit – and that’s it! Just make sure to choose a cover that fits your window air conditioner’s dimensions and seal it tight around the edges.

Downsides of Covering Your Window Air Conditioner

The main downside to covering your window air conditioner in the winter is that a cover could potentially trap moisture inside. Too much moisture can lead to rust and corrosion and could even cause damage to the unit’s electrical wiring.

To avoid moisture issues, try to choose a cover that is made from breathable material. Another option is to cover just the top of the unit so that airflow can move through the coils and control box.

A second potential issue with using AC covers is that it creates a hiding place for rodents and insects. When you cover the unit, make sure that the material is tight to the unit so that mice and critters cannot get inside.

Should I Remove My Window AC in the Winter?

Removing and storing a window AC for the winter is another option to keep your unit protected from snow, wind, and frigid temperatures.

While covering the unit is definitely effective, a post from Consumer Reports recommends that you “remove any air conditioner from a window location. During the winter months, heat could escape through the accordion extension panels on the A/C and the chassis; cold air could also infiltrate your home the same way.”

If you do choose to remove the unit from the window frame, just make sure to store it properly. It’s always a good idea to have an extra set of hands to help out when removing it from the window frame. Before putting it away in storage, remove and clean the filter, clean the condenser coils, and clean the unit’s exterior. Store it in a cool, dry place in an upright position.

People Also Ask (FAQ)

Can window air conditioners be stored in freezing temperatures?

No, it’s never a good idea to store an air conditioner of any kind in freezing temperatures, and that includes window ACs. Temperatures below freezing could potentially freeze the coils, which would render the unit useless.

If you foresee the climate in your area dropping below freezing, it’s best to weatherize the unit or remove it from the window and store it until later on.

Can you leave a window air conditioner in all winter?

Yes, you can, as long as you take the right steps to weatherize and protect the unit from the elements. You can either weatherize using a plastic bag and duct tape, invest in a durable AC cover, or insulate the unit from the inside out.

Can window AC be used as a heater?

Some window ACs offer heating capabilities. You can check out the best window AC/heaters in our guide to the best air conditioner and heater combos.

Can I leave my AC window unit on all the time?

While it’s perfectly safe to keep your window unit running 24/7, keeping the unit on all the time will likely spike your electricity bills. For that reason, it’s best to use the window unit only when you need to.

What outside temp is too cold for AC?

Running an air conditioner when it’s cold outside is never a good idea.

According to HomeAdvisor, “the limit is usually anywhere below 60 degrees Fahrenheit. You shouldn’t turn your air conditioner on if the minimum outside temperature is below that. If you do, the following can happen.”

Running the unit when temperatures get below 60 degrees could freeze the inner coils and thicken the lubricating oil. Both of these issues could ultimately damage the air conditioner permanently.


No matter which method you choose for keeping your window AC protected in the winter, just know that keeping it protected is important. If you want the unit to perform well in the hot summer months, then you must take the proper steps even when the weather gets cold.

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.