Per another post somewhere, Dometic had a run of air conditioners, around that timeframe as I recall, where the Chinese factory sometimes failed to put the tubing in a bath to remove the chemicals used in soldering.
That allowed those chemicals to slowly eat holes in the tubing, causing them to eventually fail. That post said Dometic advised them that they had no idea what serial numbers were involved, just a general timeframe.
If yours seemed to work but just would not cool you may have had some of those. If your new one has a recent manufacturing date you may now be in the clear.
2020 Georgetown GT5 34H5