Replacing aging air conditioners that are no longer working is a bit of a non decision. However what if it is still working and your furnace quits on you? This is the situation the writer is faced with. We decided to replace the AC at the same time that we are replacing the furnace. We wanted to have a new energy efficient model that will help to control our ongoing utility bills as well as increase the resale value of our home. A real estate friend of ours told us that if the furnace or the AC unit is more than 10 years old, they should set aside money to replace it. If we sell in the next 10 years, the units will still be under warranty!
There is another reason to replace the AC when you replace the furnace. If the coil begins to leak it could damage the new furnace. The coil sits on top of the furnace. Leaking water or coolant would damage the furnace causing it to rust, possibly short circuit the electric motor and other components.
We decided to replace both our furnace and replace our aging air conditioner at the same time. After all it was 28 years old and really does not owe us anything. Because it is so old it is inefficient and so we will gain from some of the savings we will get from the new system.
Everyone is in a different situation. We could have taken a chance and just repaired our furnace. This would have cost $800 with no guarantees that there would not be other problems. Apparently our furnace is known for cracks in the heat ex changer as well which we do not want to deal with.
So a big expense, but hopefully the right one in the long term.