System analysis x1 Was unable to find any burnt wires or even scent of a burning wire but I did see unit has a fresh air damper which brings in air from outside and they are doing major construction about 40 yards from the home that may be causing the smell. The unit did have a 120v uv light on main plenum and sub plenum that weren’t functional. Closed fresh air damper and Paul will monitor the smell also Recommended air scrubber to eliminate organic growth forming inside the supply plenum and to eliminate air contaminants in the home. sealed the hole in the sub plenum where the other uv light was And added the air scrubber into the main plenum. Tested the unit and system is fully functional. No other issues are visible at this time .