Air conditioners? My apt has thru the wall metal boxes for a/c units. All...

My apt has thru the wall metal boxes for a/c units. All are indistinguishable size. I currently have a Friedrich thru the wall a/c in my lr. I want to buy another element for the br, but am not willing to pay the price I remunerated for the lr unit.

My question...can I buy a windowpane a/c, the kind used in double-hung window, and just sit it in the vent box? (I do not want to buy a portable a/c with that hose set-up...noisey and ugly.)

Pros and cons.

Thanks.
Is an apple..?
Answers:    I did this within my first apartment. I stuffed insulation between the ac and wall sleeve. Make sure the water doesn't drain into your apartment.
I wouldn't recommend installing this on a wall where someone could push the section into your apartment to gain entry.