We live in an L-shaped, five-room apartment with 1600 square feet. (Exluding
hall, kitchen, and 2 baths.)

For several years we have used a 23,000 BTU window air conditioning unit
which cools the entire apartment adequately for our needs.

The only problem is, it makes a lot more noise than we like.

Would it be possible to place the entire unit on the outside, probably on a
platform just below the window, and rig up some customized ducts to handle
the intake and outflow to carry the air into the apartment? This would
involve some sheet-metal fabrication, of course, and I'm sure we would still
hear some noise, but diminished. But the cost would be a great deal less
than central air.

Any ideas welcome.