I went to do this evaporator coil cleaning and got a bit of a surprise when I split the insulation open on the furnace to coil transition.
The top of the transition was already cut off, and held in place with foil tape.


The furnace was changed out a few years ago under a home warranty.
The original furnace was a Ruud dedicated horizontal, so the transition didn't even come close to matching the new Goodman furnace.
Their solution was to butcher the transition down close to the height of the furnace, block part of the furnace outlet with ductboard, and slap a whole role of foil tape on it to make up the rest of the difference...


I'm not sure when the gobs of attic insulation got sucked in and plastered against the coil, but the duct system was replaced before the furnace was, so I suspect the mat of insulation on the coil was there before the new furnace, and they just didn't do anything about it...