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How to Winterize Your Window Air Conditioner

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Today's window ACs often have electronic controls, such as this Hisense Smart AC. Careless removal and storage may damage parts.

Today's window ACs often have electronic controls, such as this Hisense Smart AC. Careless removal and storage may damage parts.

So you live in an older home without central air conditioning. Instead of central AC, you have several window air conditioners.

What should you do during autumn to prepare for winter? Should you remove the ACs from the windows and store them? Or should you leave them in the windows? If you leave them in the windows, what steps should you take to prepare for winter? How do you maintain them so that they perform as they should in order to keep the air in your room comfortable?

I've lived in such a home in the Mid-Atlantic region for a long time. Here is the best way I've found to winterize.

Bottom line—I leave my window ACs in the windows during all seasons. I set aside time and effort in autumn to make sure they are ready for winter, following the steps in this article.

Important Things to Know About Window Air Conditioners

Before you decide how to maintain the window ACs in your own home, here are some important factors to consider.

  1. Today's window ACs are made to withstand most outdoor conditions
  2. Rain won't hurt them.
  3. Icing can cause poor performance if it builds up on the coils and the unit is running.
  4. Fine organic matter, such as cottonwood leaves blown by the wind into the AC coils, can clog up and reduce airflow over the coils causing poor performance.
  5. Today's window ACs come with parts and instructions on how to insulate the unit to save energy.
  6. .Removing and storing a properly insulated window AC is a tough annual chore. The units are bulky and heavy and take up valuable space in your home for storage,
  7. New window ACs may include remote control and even wireless. Careless removal and storage may damage sensitive electronics.

What Do Manufacturers Say About Winter Storage of Window Air Conditioners

Manufacturers' user guides typically do not recommend whether or not to remove the unit from the window for winter storage.

For example, the manual for window AC manufacturer HiSense simply says that "annual maintenance is required to help ensure steady performance." The manual offers a few suggestions, such as cleaning the air filter and cleaning the front panel and calling the dealer if you want a checkup. It says nothing about removing and storing the unit.

The manuals for Home and Frigidaire window AC units say, "If you plan to store the air conditioner during the winter, remove it carefully from the window," and then offer storage suggestions.

Other Things to Consider

What are winter conditions like in the area where your home is located? For very hard winters with subzero temperatures, a properly insulated window AC will lose more energy than locations with a milder winter, such as the Mid-Atlantic or South. In such conditions, removal and storage may be best. In my Mid-Atlantic region, winters are typically not that bad, so I leave them in the windows after making sure they are properly insulated.

Are there any sources of airborne organic matter around your home that might be blown into coils? Examples may include farm operations, fine leaves from nearby trees, and fine-grained loose soil that can be blown by the wind into your AC coils. None of these are present around my ACs, so there was no need to remove and clean organic build-up each year.

How to Winterize a Window Air Conditioner

Once I decided to let my AC remain in my window during all seasons, I followed the following steps to winterize it.

  1. Unplug the AC and neatly tie the cord. This will discourage any further AC use after winterization.
  2. Clean the air filter. Open the front panel of the AC and remove the filter. Vacuum and then wash in warm water with mild detergent. Inspect coils and vacuum if needed.
  3. Clean the front panel and replace the filter.
  4. Use flexible EVA foam board to cover the accordion shutters on either side of the unit. Cut to a tight fit (EVA foam helps absorb outside noise and provides thermal insulation. It is widely available.)
  5. Use insulation strips and styrofoam boards to seal up any other appropriate places around the unit.
  6. Check for any remaining tiny gaps and seal with caulk
  7. I do not cover the outside of the unit. This allows air to circulate through the outside coils and helps keep them dry to prevent mold.
  8. Cover the entire inside of the unit and the accordion shutters on each side of the unit with an indoor window AC insulation blanket. I use wooden strips on the inside of the blanket to stretch the blanket to fit tightly. Puff the blanket so that it is visually attractive.

It's Up to You Whether or Not to Remove and Store Windows ACs for the Winter

Look for other recommendations about how to winterize your window ACs, and you'll find many articles that say to remove and store them.

Consider all the factors listed here in this article before you decide. In some locations, removal and storage work best for energy savings. In others, it makes sense to winterize and maintain the unit in place without removing the unit.

Remember that careful removal and proper storage can be burdensome annual chores.

The choice is yours.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

© 2022 John Dove