My house has air conditioning ducts underneath my floor in the concrete and I've had my air-conditioning unit checked out and it is perfectly fine, though it does not blow cold air through all of the vents in the ground. The air pressure out of some of the vents could be better, though air is coming out, just not cold air. Cold air does come out of the vents closest to the air conditioner, though my house is 4,000 sq ft and the ground vents farthest from the unit do not get much cold air. I'm guessing that the ducts may need cleaning or the the tin ducts might be rotted? 1. Curious to hear what you think about the possibility of the ducts being rotted? Any other ideas? 2. Is it a big job to have someone with a camera come and look at the inside of the ducts? 3. If they are bad, how big of a project is it to repair them? Thanks!