Thanks for all the help guys. In my driveway, the RV is on a 6 degree slope. I moved it into the (more level) street and also used air to blow out dust from the flue and back of fridge on Saturday morning - and after an hour on gas, the fridge was getting cold. After a couple hours of loading up stuff for our trip and the drive to the weekend camp site, there was a layer of frost in the freezer when using the coldest setting.
Saturday night I had turned the coldness setting to a 4 and when I got up on Sunday, the fridge was definitely not cold enough to store food.
I put the fridge back on the coldest setting and after getting home two hours later, the freezer had frost again. So it appears that it is not properly cooling via the button setting or it didn't get cold enough just sitting there on a level surface, but was getting cold enough to frost the freezer when I was driving around?
I will also try again on electrical power when level and buy a heating element if need be.
And thoughts on this? Also, is either method more efficient (gas or AC)?