Does anyone know of a 6,000 btu or bigger air conditioner that is 18" or less wide and not higher than 16".

Answer 1

Im not certain you can even get a 5000 btu air conditioner that small.... but.. you can get a "portable" air conditioner that only runs the EXHAUST line thru the window...
With this type of air conditioner, the unit itself sits in the room, and only runs some flexible tubing in/out the window. VERY handy for especially small windows.

Here is a pic of one such -- http://www.fingerhut.com/ProductGroup.aspx?offergroupxid=35620&categoryxid=366

I remembered seeing 3 different sized models in a recent catalog, Im sure you can find others. This gives you an idea of what to look for.

Good Luck :)

Answer 2

Try to locate the new Consumers Report magazine at a store. They just did a list of portable and window a/c's. They rated them by efficiency, cooling power and I believe sizes are listed as are Brand names and models.