Auto uses electric when it is present. If you unplug, it switches over to gas, then when you arrive at campsite and plug in, it switches back over to gas.
You can force gas only, which is a good way to cool faster and test the propane option before towing a long distance and losing everything in the fridge because it wasn't cold.
In other words, gas to cool and tow, electric to camp (when avail), and gas only to force cooling.
I didn't design it, so can't say for certain, but it makes sense when I think of it this way.
Oh, get some bars for each shelf of your fride and two for freezer. The first time a jar of pickled does not fall out on the floor when you open the fridge the first time at your campsite, you'll know it was money well spent ;)
