Thank you for your last answer. You mentioned that the blower could be responsible for the scratch-like sounds coming from the duct. What do you recommend? I have a homeowners policy that covers air-conditioning but I didn't know if this was something I could fix myself. Thanks

You should probably take a look inside the registers if you can, and check the screws and connections on teh outside. Could be a rattling part.

Also, next time, post a reply to this thread (reply or 'answer this question') instead of making a new thread.

Hello...it appears that some plastic coating inside the duct is loose and is flapping when the air hits it. I am tempted to patch it up or mess with it but I don't think I should! Does that sound like a big problem or ??? thx