Performed heating maintenance on 4 year old Comfort Pro/Goodman unit. Resecured ‘r’ wire on the low voltage bus on the furnace control board. Checked all safety switches. Cleaned flame sensor. Inspected blower compartment and found blower wheel to be clean and balanced. Installed new MERV 16 filter. Flushed condensate drain with water. Temperature rise is within limits. All electrical amp draws are within limits. Dina let me know that there is very little air flow out of one of the registers in the family room upstairs. I inspected the duct work that I had access to to see if I could determine the problem. I removed a panduit tie that was restricting a duct but that didn’t resolve the problem. I put my inspection camera about 10’ down that duct run and found a lot of rat droppings and as though a rodent was eating away at the duct, it was clogged up with a lot of insulation. I told Dina that I would see if we have a camera that can reach further in the duct before