Air Conditioning - Window A/C in my attic?

Hello,

I have a 2-story 2400 sq.ft. home (1000 sq.ft. up/ 1400sq.ft. down). The home only has central A/C upstairs where all the bedrooms are. I get a very good breeze and it usually stays pretty comfortable even on hot summer days. I usually only turn on the central A/C on warm nights for sleeping and sometimes to cool down the downstairs a little.

My kitchen and garage have no upstairs above them. I was wondering if I could put a large window unit A/C in the attic above my kitchen/garage w/ one large vent blowing into the kitchen. I can build my own duct work and I was thinking I could set the window unit in a tray that would drain the evaporator water out one a soffit vent.

I know this is kind of a hokey setup, but it would only be temporary and not used all that often. I just don't like the fact that when I try to cool off the downstairs w/ the upstairs central A/C that the unit pretty much runs non-stop. I would rather replace a fairly cheap window unit than replace an expensive central A/C condenser/compressor unit.

Ideas? Possible? Bad idea? Suggestions?

Thanks,
Rich

I wouldnt set the a/c unit in the attic, too hot! You need to mount the a/c outside and build a supply and return for it.
Attics can heat up to 140+ degrees, I saw mine get to 160 once. That hot air would fry your compressor. Even if your attic was not that hot, it would heat up quick with that unit running in there.
Why dont you consider a mini split unit for the kitchen area?

What is a "mini split" system?

Also, what if I put the window a/c in my unfinished basement where it stays cool and install 2-3 floor ducts in places where I plan on having central a/c ducts in the future?

What is a "mini split" system?

Also, what if I put the window a/c in my unfinished basement where it stays cool and install 2-3 floor ducts in places where I plan on having central a/c ducts in the future?

A mini split unit has the condensing unit outside and the evaporator hangs on a wall in the house in whatever room you wish to cool. They also make multiple evaporator units for cooling several rooms but they are pricey.
Mini splits are more efficient and much quieter than window type models.
You could set the a/c in the basement, providing the area is large enough that it wont heat up while the unit is running, those units blow alot of hot air out the back and could heat up an area real quick.
You also need to remember that these little window type units dont throw enough air for too much ductwork, you will need a large unit to get the air through the ducts.