Bonus room Dampers

[bjr68]

My home is only a couple of years old with three EWC dampers that were installed to control the heat/AC in a bonus room above my garage. I had the installer return several times to remove a high pitch howling noise when the furnace or AC runs - especially at start up. The noise is within the ducts of the first floor and nearest to the furnace. As far as I know the installer never removed to dampers to inspect them. He just made adjustments on the outside the units. Any ideas on how to rid my home of the howling noise?

[Paul Z.]

I need a little more info. Please call 1-800-446=3110 X490.