I received 2 estimates for replacing my air conditioner. I currently have a 3.5 ton Ruud unit from 1989. It still works, but the tech who serviced it this spring said he had trouble getting it started and once he got it going, it was freezing. I was told by both estimates that my evaporator coil is 3 tons, and they would replace it with a 3.5 ton coil. However, when talking on the phone with the second company today, he said the coil difference concerns him and I might need to replace my furnace. The furnace was replaced in 2003 by the previous owner. It is a York G1FA036S17A. The furnace works fine, and I am really not in a spot financially to replace it right now. I was hoping to get a few more years out of it. The first company did not have concerns with keeping the current furnace. The company recommending replacing the furnace is coming back out to look at it tomorrow. I understand that it is ideal to have your ac and furnace replaced at the same time, but is it necessary in this situation?