Old unit is still running, but it's got to be on its way out (20+ years old). It will probably be replaced with a 410 refrigerant unit, and so my question is: With a lineset run of 40 feet, with 8 feet of that being a vertical run (the unit is in the attic), will it need a larger-diameter-than-usual lineset? If so, I guess that solves the question of clean vs. replace on the lineset...