One question we get asked each year as winter approaches is if the outside air conditioning unit should be covered for the winter. For many reasons, the answer to that question is no; it is not necessary to cover your air conditioner for the winter.
Why? You might ask. The most important reason why not to cover your air conditioner is that it is just not necessary. Your HVAC equipment is designed to withstand the hottest heat of summer, and the extreme cold of a Minnesota winter.
By putting a cover on your air conditioner, you are creating a nice warm, safe place for rodents to nest during the coldest parts of winter. This can lead to chewed electrical connections that will require a service call to repair come summer.
A covered AC also blocks proper air flow allowing a buildup of moisture under the cover, resulting in mold and mildew. This can decrease efficiency in your AC in the summer by restricting proper air flow. The increase in moisture can also damage and corrode the electrical connections.