Out for annual heating maintenance and found new system down stairs duct work appears to have metal rust in it. Removed register in bedroom and vacuumed up a good amount of stuff, it is blowing onto the desk below. Put vacuum in duct to clean line as best we can. Cleaned up dust on desk. Keep an eye on it, if problem comes back or gets worse call and we can come back out and inspect some more. Tested system heat and cool all ok at this time. Checked filter in ceiling ok at this time.