This can be a major source of cold air coming into your home in the winter. Air conditioners, as you know, exchange the warm air in your room with the cool air that it produces. That warm air is then exhausted out of the unit to the outdoors. However in the winter when you don’t have it on, allows the cold air from outside to enter your home making it cold and pushing up your heat bill. If you can, you should remove the window unit and reinstall it in the spring or summer.
If you can’t take it out of the window or have a unit permanently mounted in the wall, then you will need to by an air condition cover. These are installed on the exterior of the air conditioner. You will need to know the dimensions of the unit in order to buy the right size cover. The cover will then go around the unit and will help prevent cold air from coming through the unit in the window. While you are at it, check the way the unit fits in your window. If you feel drafts there, you will also need to air conditioner foam seal to go around the unit. You will also need it to seal the gap between the windows too.
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