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That can be from a blower wheel coming loose or even a mouse that has gotten into the furnace and into the blower. In my area we see this quite often during cooler weather. Some examination would need to be done. IF you have an outside inspection panel you can remove the cover over the blower and inspect that area. Look for any cracks or missing pieces in the blower. Let me know what you find and we can go from there. All follow ups are included in our fee.
Just checking back in to see if you were able to resolve this issue or if you need additional input from me here?