Thank god I'm not getting smarts, I'm just a turn it on and it better work sort of bloke, figuring why makes my head spin............
I have worked out that the so called myth of fridge operation on 12v when travelling is because most fridges are fitted out by he builders, therefore even if lucky enough to have it installed correctly the wiring is usually rubbish, remember the infamous Jayco Birds Nest of wires, no explanation should be needed.. So not really a Myth as it does happen, (not to mention the lunch stop with kids and the fridge door kept open for 30mins)..... My old fridge in 36 or 38 degs between Winton and Julia Creek had a 12v fault (forgot to turn it on) it lost 3 degs over that time, this being after I fitted it out properly so its generally not the fridge but the fitting out, if I hadn't sorted it out things would have been different, while I have not fiddled with a lot with compressor jobs the few I have looked at have suffered from the same pith poor fit out.
You do not have to have too much of the "Smarts" to be successful @Drover . As you have stated before , common "dog sense" can solve most problems.
I could not agree more on your comments about builders fitting fridges. None of them appear to follow the makers instructions! And as for wiring, that is too much like hard work (nd cost) modifying the tug's system, as the tug's wiring is usually not set up for carrying heavy current to van without voltage drop.