My AC unit isn't cooling properly. Had someone come out and tell me the evaporator coil has a leak and needs to be replaced. My question is whether I should simply replace the evaporator coil or replace the entire system. I have a 4 ton Trane system that is 11 years old. He didn't say there were currently any problems with the compressor/condensor. He did say that the new coil would have to be retrofitted to work with the Freon in my existing unit. Considering the age of my system, if my compressor goes out in the next couple of years and I have to get a new one, am I going to have to replace the coil again or have issues with the fact that at one point it was retrofitted to work with Freon? Any recommendations would be appreciated - thanks!