One question we get a lot is, “Do I need to cover my AC in winter?”
The answer is no. You do not need to cover your AC for winter.
Why you don’t need to cover your unit in winter
The outdoor AC unit is built to withstand harsh weather, from rain to snow to any extreme weather you might get over the course of winter. Additionally, when the AC isn’t running, it won’t suck in any dirt, so you don’t have to worry about your AC getting clogged with dirt over a long dry winter.
The main thing to worry about in terms of your outdoor AC unit is moisture getting in. For this reason, putting a cover on is worse than no cover at all, because a cover can trap moisture inside the unit and won’t allow it to dry out. Also, a cover will entice rodents and other small animals, as they’re looking for a sheltered place to hide from the weather, and a covered AC unit provides such a shelter.
If you want, you can cover it during the Fall to keep out leaves
There is one time of year where you can cover your outdoor unit, if you wish, and that is during fall. The unit may be built to withstand rain and snow, but it is not built to keep out leaves and other types of fall debris. Leaves can collect inside and moisture will build up which can cause corrosion inside of your unit.
However, if you decide to cover your AC unit for fall, only cover the top. The cover should not cover more than 6 inches of the side, as otherwise, that dreaded moisture will collect and could damage your unit.
Do not cover your AC unit during the winter. But you can cover the top of it in fall to keep leaves and debris from collecting moisture inside.