Our home is 60 to 70 years old pier & beam. We moved it to our farm 20 years ago. The a/c unit has always gotten free air from under the house as return air. We had to replace the unit 2 years ago. They said by law they had to move the return air to the attic thru ducting rather than the free air under the house. The vents are still open thru out the house but there are no vents leading outside. Shortly after the new a/c we noticed original hardwood floors buckling. Floor guy says it has to have water....NEVER HAPPENED. Plumber says there are no leaks under house. A/C guys says it has nothing to do with the return air. House level company says foundation is fine but for $4000 they could come do some maintenance and tighten everything up. No one can give me an answer as to why the floors are buckled. Who do I call now?