[ironpumper]

Carrier high efficiency furnace: at both high and low blower speeds hear a high pitched whistling noise from the heat vents in the rooms adjacent to the furnace. Cannot detect noise when doing a visual in the furnace room itself?

[T-Top]

Check your return air filters. Does this system have zoning dampers? Make sure all supply grills are open. Some times duct tape can come loose and give a odd sound. You may have to investigate a little further to locate the or pinpoint the sound for us to help.