How to Make a Vent Cover for an Air Conditioner Wall Unit for the Winter

Measure the height, width and depth of the air conditioner condenser on the exterior of the house with a tape measure. Write down these dimensions.

Purchase enough breathable tarp fabric to cover the entire unit with about 4 extra inches on each side.

Mark the dimensions onto the fabric with a tape measure and a straightedge then cut along the lines with heavy-duty scissors.

Place the tarp over the air conditioner so the top edge is flush at the point where the air conditioner meets the building. Apply a strip of duct tape along the edge of the tarp to hold it to the air conditioner securely.

Pull the tarp down over the air conditioner and align the edge of the tarp where the air conditioner meets the building on the bottom. Apply another strip of duct tape along the bottom edge of the tarp to hold it securely.

Fold the right edge of the tarp flat along the right side of the air conditioner and apply a strip of duct tape to seal the edge of the tarp at the point where the air conditioner and building meet. Fold the excess tarp from the top and bottom across the right side of the air conditioner, similar to the process of wrapping a gift. Tape these tarp edges securely across the right side of the air conditioner.

Repeat Step 6 for the left side of the air conditioner. When you're finished, the tarp should cover the air conditioner completely in a secure and uniform layer.

Apply another strip of duct tape around the entire edge of the tarp where it attaches to the building to ensure a tight and secure covering over the air conditioner.