I had ARS come out to clean the furnace and check the faucets and drains. They were running a special and the appointment had been rescheduled twice. When the first technician came to do the cleaning he looked at my 39 year old furnace said the furnace was older than he is. He called a coworker, and told him that he didn't know what to do because the furnace was so old. He said that he was scared to hook up any of his monitors because it might "blow up." The person he called told him to just take the readings and close it up. He said do not do anything else to it. Turns out the heat exchanger has a crack in it. The first tech did as instructed, wrote up the job and left. He suggested we call American Home Shield (AHS) so we could have it replaced. Called AHS and told them that we had the furnace serviced and the company told us that the heat exchanger had a crack in it. They sent a second guy from the same company to look at it. The second guy said that the crack came from neglect, not age. So, AHS said they would not replace the furnace based on what the second tech said. I called ARS to speak with the second tech and was told he was with a customer, but would call me back when he was done. Have not heard from them yet.