How To Winterize A Window Air Conditioner

Posted on: 21 November 2016


If you have a residential window air conditioner, it is important to winterize the unit. Winterizing your air conditioner makes the unit last longer, and it saves on utility bills. An improperly sealed unit allows air to escape.

Storing removable units is easy. All you have to do is remove it and wrap it. You can still winterize units that cannot be removed. Here are some tips to winterize a window air conditioner.

Prepare to Work

For this project, you need:

  • tape measure
  • rag
  • weather stripping
  • double-sided tape
  • putty knife
  • scissors
  • plastic or fabric cover
  • insulation
  • garbage bag (optional)

Disconnect the power cord to the unit. Inspect the unit for insects and debris that could prevent it from working. Wipe moisture with a rag, and let it dry. Removing moisture prevents the motor from rusting.

Empty water from the drip pan, since water left in the drip pan could freeze. Clean or replace filters. Run reusable filters under water to clean. Clogged filters reduce the efficiency of the unit.

Measure the air conditioner to determine the size cover you will need. It is ideal to buy a cover made for the brand. Some hardware stores sell fabric covers.

Add Insulation

Cut strips of foam insulation the length and width of the unit. Push strips into the gaps in between the window frame and the air conditioner with the putty knife. You may use spray foam insulation, but be aware, it expands.

Attach the Cover

Secure the cover on the the unit; applying weather stripping where needed to seal the edges against the window, if needed. Get measurements of the outer most wood trim., then add an additional inch to all sides. Fasten the plastic on using the double-sided tape, and push the plastic firmly on the trim.

If you have a fabric cover, they should just slide on the unit. Fabric covers may be attached year around during thunderstorms. Another option is to cover the outside with a garbage bag.

Winterize a Removable Unit

If the unit is removable, unplug it, and take it from the window. Remove the cover and insulation.

You may likely need an assistant to help you. Clean the air conditioner, cover the unit with newspaper or other wrapping material, and store it in a cool, dry place off the ground. Storing the unit high will prevent rust from moisture.

Winterizing a window air conditioner is a simple process that saves money. If your air conditioner doesn't run properly, contact an HVAC service like