Hello. I am just a random guy with a dumb question. I need to have my furnace replaced. Question is whether I should replace my home A/C at the same time. The A/C works well but it is 16-17 years old, so probably pretty inefficient and -- as with all of us -- it won't live forever. Our contractor (who is very reputable and I trust) says it is more convenient for them to do both at once, and thus cheaper for me (labor savings). To get the A/C too will cost me an extra $ (for a Carrier 5 ton unit, with all installation, etc.). Should I do both,or wait till the AC dies before replacing it?