[Mikendebbie]

I could not find a pic of the ductwork in a 2014 model - but it has the racetrack duct system. The ductwork circles the AC units for the length of the coach. If you assume the AC support frame opening shown in my screen shot above is (say) 24”x24” - and assume the ductwork section is (say) 2”x14” - then you can measure the approximate distance from any vent in your ceiling to the main trunks of the racetrack duct system. I don’t know that branch ducts exist in the ceiling because you never see them in the factory tour videos. Even if you have a register in the ceiling that you think may be on a branch duct - use the assumptions I lay out to measure your approximate length. You won’t be measuring to the nearest millimeter - all you need to know is “it’s about YAY long”.

Frankly - you will only be able to insert short pieces of PVC into a collapsed section of ductwork thru the small vent or return opening.

The screen shot below demonstrates a duct collapse by squeezing a section. The collapse does not extend further down the duct section. I suppose a full collapse is possible - but not likely.