AS the other posted stated, if you have a closed Building that is not at least 2000 sq ft, you will have overheat in the garage. The roof top unit removes the HOT air from the outside Condensor and dissapates it into the open air. If in a garage, then their is no place for that hot air to go and after awhile the AC cannot remove the hot air from the Condensor. So, just leave a door and a window open in the building and you should be OK Having a small Box fan blowing air out of the garage will be useful too. Doug