[JRTJH]

As long as you're not opening and closing the refrigerator, 1-2 hours is not a problem. If you're going to be in 90F + weather, opening and closing the refrigerator to get drinks at rest areas, or other similar activity, I'd expect that by the time evening rolls around and you're pulling into a campsite, you're going to have "mushy" ice cream if it's even still frozen. If you don't open the refrigerator, it should be OK for 4-6 hours in the same 90F + tempterature. We've found along the way that if we leave it running, things don't condense in the freezer and it doesn't need defrosting as often. So, when summer starts the refrigerator gets turned on and when we winterize, we turn it off, defrost it, clean it and prop the door open. I don't think we've turned off the refrigerator (or the propane) from the start of camping season until we "put 'er up" in the fall is at least the last 30 years. Once it's turned on, it's on for the season....

The important thing to remember about absorption refrigerators (IMHO) is that it takes a significant time to cool down, once that cool is lost, it takes another substantial length of time to regain the cold. It's better to keep it cold than it is to let it warm up and then try to recool it while camping.