I sent an inquiry to Dometic, and followed up with a tel/con. Some of you may think I am over-analyzing, but I am frequently leaving my caper on uneven off-road ground while hiking in to fish various rivers. I would just like to know if I am damaging the unit by leaving it on with no manual shut-down. According to what I found out,.. I am. For those of you who would like to know what I found out read on.
According to the gentleman that I talked to, there is a tolerance of 3 degrees fore and aft, and 6 degrees side to side that the unit is designed to operate within. (Now, if nothing else we know our sleeping tolerances, but I have a few too many sometimes and I have a tendency to overlook this tolerance) If outside that tolerance, a restriction will occur and the ammonia fluid solution will over-heat resulting in a crystallization blockage. Evidently this crystallization can happen immediately, but usually is something that is cumulative and layers each time. Also the unit does not shut itself off. If done consistently over a period of time, like Pvstoy says, then you end up with a brick instead of a cooling unit that will need replaced.
When I asked about DC operation, he said that he needs to formally state that the specification is the same for all three operations. Off the record, he indicated there was not as much heat in DC mode and therefore the crystallization formation would not be as pronounced. However, in the out of level condition the free flow of the ammonia coolant exchange from liquid to gas is still not present so neither is the ability to cool. So, no better in DC mode and best to turn it off.
So, net of it is,... If you are going to consistently be parking on ground out of this specification, you need to manually shut down your refer, otherwise over time you have problems and it's cooling capacity will degrade. With this decrease in cooling capacity an increase in energy would be required, thus less efficiency.
This is my understanding of my conversation. Possibly I misunderstood. It is also possible that the individual that I talked to didn't really know, but it sounded good to me. So,... Shut it down if your sleep angle is exceeded, it won't turn itself off.