[Bernica]

The right way would be to install a split-system similar to what you have in your house, with the compressor / condensor outside and the evaporator and fan in the garage. Just get a small vertical unit that can sit in a corner of the garage and run one outlet, or some distribution ductwork from the plenum box to distribute the air, then you run a condensate drain to the outside of the garage. It shouldn't take a very big unit. Depending on how well the garage is insulated, use 300-400 square feet per ton of cooling (1 ton is approx 13,000 BTU's). You can use around 600 square feet per ton in a well insulated house.