Art,

The're called air shafts and they provide ventilation. You don't tell us
how big your apartment is, how high it's ceilings are, or how big your
window units are. You do mention that the windows have considerable air
leak.
So fix the leaks or get the landlord to deal with them. This probably
will involve buying a tube of caulk. When you reinstall the AC units next
Summer pay close attention to sealing and insulatins around the units. A
lousy install is a guaranteed leak. If you have high ceilings consider
getting a ceiling fan (with your landlord's permission).

Dave M.