Well, I can only speak of my experience as a kid when I was still living w/my parents. Every single, stinkin' Fall, we removed 3 air conditions from our house's windows. And every single, stinkin' Spring, we put them back in. Two of them were on the 2nd floor and one was on the 1st floor. Worst, my Dad and I carried them to and from the basement!!! If I had to do that today, I'd look into a way to 'convert' the AC units into nightstands, or something.
Anyways, you see these units sealed up all the time in neighborhoods around America. And there are probably as many ways to do it as there are units in the window. The key, of course, is to insulate AND prevent cold air from entering into the house. And, at the same time, try to protect it from the elements from freezing and thawing water and snow. Our house's particular units lasted a LOT of years by taking them out of the windows. I can't speak of any experience from leaving them in. But if I were you, I'd remove them if you can. DO get help and don't do it from a step ladder outside the house. Do it from the inside w/your feet planted firmly on the floor. I suggest you set 'something' on the floor in front of the window to set the unit on once it's IMMEDIATELY removed from the window so you can 'decide' what your next 'move is going to be. It's no fun trying to do that with 100+ lbs. in your hands and in that of your helper's too. (A milk crate works great.)
Heck, maybe you can leave it right there (under the window ledge) and cover it w/something 'nice' for an end table. (Now why didn't I think of that 25+ years ago ...)
My best to ya and hope this helps.
Jay J -Moderator
PS: God Bless America!