I finally scheduled a date for the installation (A/S ycx036gm). They will install only one return, since there was no previous returns as the house has a flat roof, and the original equipment was a swamp cooler. The house layout is pretty open, and it's only 1000 square feet (two bedrooms only).
In any event, this is a 3 ton package unit, so I was wondering what would be the correct size of a single return. As some of you might know, many houses in Arizona, specially older ones like mine (1972) are built with brick, adobe, or block, which means that they are harder to modify. However, I do see that a lot of houses with these package units and only one return duct (or so it seems to my untrained eye, hehehehe).
Oh, and last but not least, I ordered a VisionPro 8000 (it was only a few bucks more): was that overkill, since this is not a variable speed or two-stage system?
I thank you for your help and look forward to your response.