re: How can I cool a bonus room above the garage without using a window unit a/c?

Mini Split is basically just a miniature version of your central air setup that is made to cool a single area. They are often used to cool certain areas of hotels, etc. More BTU than a normal window unit, but not as much capacity as a central air.

Basically have one unit on the inside of the room with a fan blowing cool air and copper lines to a small outside unit.

Mini split