LVSteve
Member
Good planing but unless your garage is is under Air, I do not agree with #4
The issue is that the air handler/furnace is in a niche in the garage. While the air circulating through it is not getting heat from the garage directly, that heat is all around it as the metal trunking and the air handler structure absorb heat form the surrounding air.
I found out some years ago that if I came home from work about 430pm and put my car in the garage, it had a noticeable effect on keeping the house cool. It let in the ambient air from outside AND inserted a 3500 lb chunk of heated metal, some parts of which are at 2-300°F or more. When I started leaving my car outside until later, I immediately noticed that the A/C ran less.