I have an odd problem with my kitchen sink and I'm completely stumped. Double kitchen sink with disposal backs up through both drains. There's no blockage! All the obvious stuff is clear...p trap, T, tail pieces. Ran snake 25' well into main 4" line. And has worked fine for years...all of the sudden. If it backs up, I remove AAV and water drain immediately but if I run it with AAV completely removed, still backs up? Seems like so kind of air trap or something? Any help would be great
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