Just got new ac. What can I do to cover top from debris in compressor

you can any type of screening, single sheet or double or triple the screening, you can put medium size rocks on each corner to hold it in place

Do not cover the unit when it is in use. You can cover it for the winter months though by using a thick piece of plastic and then lay rocks on top of it. Or, you can buy a pre-made A/C cover. During the time that the unit is in use, keep grass and weeds from growing up against the unit. Keep the unit level and you can hose off the unit with a garden hose. Just make sure the unit is OFF before you try to clean it out with the hose.

I used bird netting and secured with zip ties. held up for years.

Hi, I have a lot of Cotton Wood tree's growing here in the mid-west and to protect my a.c.. I make a cover for the unit outside, made with screen door mesh. You can buy the screen door mesh by the roll at H.D. stores, it is not that expensive.. I use also use it to strain paint for lumps before painting, and many other things. I hope this helps.

Make a box with a top that opens

Steen door mesh,inside your box

Don't put anything on your AC unit while it's running. But during the Fall and Winter when it is not in use, you can cover it with a tarp or even a grill cover. Secure your cover with bungee cords or even rope. Clean it in the Spring.

I agree with Papoose03, Deanna, and Aljosjer. Do not cover the top when in use. It needs the air flow to dissipate the heat off the coils to cool the refrigerant. You can strain and prematurely burn up the compressor. Even screen material on top will restrict the air flow from the unit. You can wrap the coils with screen material to keep debri off the coils and easier to clean as Deanna suggests. I also have a lot of cottonwood trees so I took some window screen material stapled to two boards, glued on magnets to the boards and wrapped it around the unit. The magnets hold the screen material on the unit. I just brush off any debri. When the unit is off for the cool season you can cover the top with plastic, tarp, piece of plywood, etc. I don't advise covering the whole unit as moisture can build up from freeze and thaw. Mold can form on the base start rusting process and eat away at the coil fins along the bottom.