If you park any RV and its operating refer very far off level for an hour or more... uh, oh. You may have caused a blockage in the system that usually cannot be "undone". It happened to me twice in my first years owning a motorhome; I got off too easy the first time cuz the warranty covered it. But I didn't learn my lesson; while in a panic over not being able to start the rig one time, and distracted by trying to make repairs, my coach was fairly off-level for an hour or two. That oversight cost me $800 for a new cooling unit. You'll be lucky if that's all such a mishap costs now, 22 years later.
Today's refers are a bit more tolerant, and 3-6 degrees off-level may be okay. But you should still make every effort to park your rig fairly level whenever the refer is on, so crystals or condensate don't end up in the wrong place and block the evaporative (gas) side of the heat absorptive operation. I use an inexpensive single central-bubble level on the bottom flat section of the refer or mid-shelf; as long as the bubble is mostly in the center ring of the level, it's good. I've also used a ball in the center of the tile floor - if it rolls readily in any one direction, I adjust the coach accordingly. Simple enough.
-Joel
