The 9 Best Air Conditioner Covers

If your outdoor unit sits under trees, the Modern Wave Mesh Top keeps leaves, twigs and seed fluff out of the fan without sealing up the coil. Only the top is covered and the mesh stays open, which is the one style heating and cooling pros say can stay on a unit that might switch on. Four bungee cords with coated hooks hold it down in wind. It does little against rain or snow, and the mesh trims airflow slightly.

The Jeacent Winter Top is a solid, waterproof square that bungees over the fan grille, so rain, ice and falling branches stay off the blades while the sides stay open. Leaving the sides bare lets damp air escape, which is why trade advice favors a top cover over a full wrap for the idle months. Coated hooks spare the paint, and it goes on and off quickly. It has to come off before the unit runs again.

For a unit that's shut down for the winter, the COSFLY Full Cover wraps the top and all four sides in coated, heavy oxford fabric. Vents let damp air escape, a drawstring hem keeps wind from lifting it, and a slit with a buckle closes around the refrigerant lines. Two padded handles help when you pull it on. It runs large on some units, so measure first, and it should never stay on while the unit runs.

Built for long, wet winters, the Porch Shield Square uses PVC-backed polyester, doubled stitching and taped seams, so water can't wick in through the needle holes. An elastic hem with a drawstring snugs it down, and a side opening clears the pipes. It tends to look new after a season and hold up for several more. The coated fabric breathes less, so lift it on dry days to air the unit out, and keep it off whenever it runs.

Small window units get a cheap, sensible shield in the Luxiv Window Cover, which slips over the outside half and buckles on with two straps. Its waterproof shell has a silver lining that keeps rain, snow and some of the winter draft out. Bob Vila's editors chose it as their outdoor window pick. It's sized for units up to about 7,000 BTU, it runs a little big, and it adds only modest insulation.

If cold air pours through your window unit all winter, the i frmmy Insulated Cover adds real layers: a waterproof shell, a foil sheet and a soft foam lining. Metal-buckle straps cinch it tight, and the bottom panel can be cut to fit around a support bracket. It holds up well in hard winters and cuts drafts in a way you can feel. It's bulky to store, and fit matters, so measure the part outside the window first.

Bigger window units, up to about 12,000 BTU, fit under the BOLTLINK Window Cover. A thick oxford shell with a waterproof inner layer keeps snow and sleet off the coils, and it has a good record through snowy Midwest winters. Two buckled straps hold it to the case. Putting it on a high window can take half an hour, and the straps can work loose in wind, so check them after the first storm.

Cold air also leaks through the vents on the room side, and the COSFLY Indoor Cover handles that half of the job. It's a quilted, padded panel with an elastic edge that wraps the front grille and a hole for the cord. Left in place all winter, it blocks most of the chill that seeps in. Fit is the weak spot: it runs small on some units, the cord hole may sit on the wrong side, and it can slip.

Frost King, a longtime maker of window insulation kits, sells the Frost King AC2H as a no-frills outside cover for window units up to about 10,000 BTU. It's reinforced plastic sheeting held on by an elastic strap, cheap enough to treat as a one-season cover. Larger sister models fit bigger units. The plastic doesn't stretch, so buy the size above your unit, and it's thin enough to tear in a rough winter.