I am building a home in TX and want to upgrade my 14 seer carrier a/c to 16 seer (4ton and 2.5). What is the price difference. I think I am being taken for a ride. I am having hard time understanding why it is so much to upgrade the a/c units. We will pay the cost difference between the 14 and 16, but equipment is equipment. If the a/c was already going to be place in the home why are we the consumer being charged basically double of the cost difference for installing a different size? It's still an a/c unit.