It's not the temperature of the WATER. It's the air you are using as a heat exchanger. I go into a LOT of garages, every day. The only place worse for a chiller, is the attic. Put it outside. If you put it inside, you are just heating up your house, which will then have to be cooled by your A/C. None of these are very efficient - why dump heat into your house, that you then have to dump back outside with your A/C unit. Just put the chiller outside where it belongs. By putting it outside instead of in the garage, you can halve the size of your chiller.