Just had my units checked because the A/C is not very efficient in the summer. The furnace is also in question. They work, but are 26 years old and the house just isn't as cool or warm as before. We had them checked out and they are both at the end of there lives. 12k for both and that is the middle of the road units. Two years ago the roof about same price. It's necessary but the thing is I don't believe we will be in this house much longer. I better recoup some of this $$$ when we sell.