Central heat and air unit
 

Done my yearly maintenance on my furnace/Ac unit, Hadn’t opened up the A coil On this unit so curious how dirty and rusty on 16 year old unit.

Actually A coil was not that dirty, end caps surface corrosion, and pan little dirty.

Guess what found in my furnace carbon dioxide vent?

Wasp nest and mud cakes. As I disconnecting the furnace vent that goes out to roof, crap felt down into the boost fan. Removed the boost fan dumped the crap out.

Those little fellas get around, everywhere.