I am guessing that the air conditioner solution will not work. Supposing you want to cool your hanging room to 40 degrees, I'm guessing some other technology will be necessary. What about talking with someone who works on walk-in freezers or coolers? I imagine every grocery store has such rooms and these must require maintenance, so I guess such people are around.
If you insulate the room and get the air cool, your idea should work very well. I just have my doubts that a standard 110 VAC air conditioner is the appropriate device for the job . . . but maybe I'm wrong.