An outdoor cooling system is designed to be an all-weather device, however nothing should impede its airflow since heat transfer from the indoor unit to the outdoor Heating as well as Air Conditioning unit requires that this outdoor system radiates energy to the atmosphere! You could destruction your Heating as well as Air Conditioning system when you cover or block the outdoor unit. You may have thought of protecting your cooling system while in the off-season to prevent elements of weather from destroying your unit, but your outdoor unit is designed to withstand, but any dirt or dust that may gather on your cooling system is washed away with rain and snow, however while you may know that rain and water will destroy the unit, its internal unit is protected against water, and rainwater has a designated path to drain the water out to prevent your unit from accumulating moisture, then however, you may need to cover your unit after Summer to prepare for fall because your outdoor unit is not built to keep out debris, leaves, seeds, or nuts, then during fall, leaves and seeds get into your outdoor A/C unit, and this may cause moisture to build up to where seeds and debris have accumulated; The moisture build-up will end up causing corrosion to your unit and blockages to your drainage system; If you choose to make your cover, it is advisable only to cover the top of your outdoor A/C unit, covering the entire unit will lead to moisture getting trapped inside, which will cause your unit to rust and corrode. When you fully cover up your unit, you will have gave rodents a venue to stay instead of repelling them away.