Converting to a dual evaporator air conditioner

[ericjohn]

Does anybody know of an easy and practical way to set up a central AC with dual evaporators? I live in minnesota and have an amana 80% variable furnace in my rafters of my garage to heat it in the cold winter months. Would it be easily feasable to install an evaporator for this furnace and interconnect it to my existing or a new(i'm thinking of replacing) central air conditioner that already cools my house. If I were to start from scratch would a 2 stage air conditioner be better? How would you size this unit? Would I need to use solenoid liquid line valves for terminating process or diverting? Some ideas or insight would be nice. I have 12 years experience in heating and air installation and service on residental and light commercial systems. Just would like to cool my garage reliably and efficienctly without adding a seperate a/c. I have a 2 car garage.

Thanks Alot! Eric