A window a.c. unit discharges hot air from one side and cool air from the other .
providing the majority of the hot air goes out the window you will feel a benefit ,however it will only be as good as your seal between hot air side and the window.
you may be better off placing unit in a doorway of a spare room with window open and block off as much of doorway as possible around unit.
mr A.Cooltip
July 2007