hello gentleman, i am thinking of buying a home that was built in 2004 but did not have an a/c unit installed. my question to all of you is would this be an expensive upgrade? also my real question is would this be possible with the current heating unit? if this is not enough information about the heating unit what i need to look for to see if it would be upgradable to accept an a/c unit. i aapreciate your answers and your input.