I just bought a house that has the original Rheem 3 ton outside from 1984 but due to water in the vents, the previous owner sealed the vents in the slab and ran them overhead and put in a Trane XE80 updraft unit which I am guessing to be max 9 years old. I like the Trane name and brand and am happy with the XB13 outside condensor but after 5 bids for the unit, I have gotten varying info. All bids were for Trane XB13's but some vendors said the coil was fine, TXC036C4HPB1, and that it was built to go to 14 seer. Some said it would be ok but I would not get the full 13 seer but since I won't be in the house very long and consider it an investment not to go to expense to replace coils and another flat out said that it needed a thermal expansion something else performance and unit life will suffer and that they wont put a unit in without it. Can someone help clarify if I need this or not? Seems weird to be getting such a range of answers from vendors that are exclusive trane dealers.