Last summer the RM1350 in our 2019 260RD stopped cooling on LP while we were boondocking. Would cool on AC just fine but that has mostly stopped. Ran through a litany of diagnostics and checking different parts. Fans come on, AC heating elements work, LP pressure is tested and within spec, igniter works, thermocouple works, no errors on the display or when running the test mode from the upper board, all fuses checked, reset button on the thermocoupler thingie at the bottom of the flue has been checked, gone over everything with a multimeter, cleaned the flue, new LP burner, swapped lower boards for the heck of it, burped the cooling unit, no major changes. After burping the cooling unit, it cooled again on AC. But since all we really do is boondock, LP operation is more important so I switched it to LP and lost cooling in both modes. I admittedly did not burp it as most people I've seen online suggest, I just flipped it upside down, rocked it back and forth a couple times before flipping it back over and put it back in. I definitely heard the chemicals sloshing around, and there are zero signs of any chemical leaks from the cooling unit. I have noticed that the back wall of the freezer and the cooling fins are occasionally 15-20* over ambient on AC and LP so I believe it is heating the cooling unit as it should. The fans still kick on as well.

At this point, the only thing I can figure is the chemicals in the cooling unit have crystalized somewhere and are preventing everything from flowing as it should. I'm leaning towards the burping "trick" again, but leave it upside down overnight to give the chemicals a chance to do their thing. I'd really rather not throw a new cooling unit at it if I can avoid it, especially since the one in there has worked on occasion.

Anything anyone can think of that I'm missing?