Wopchop - Thanks for advice about fans. I hope I don't end up with 4 fans - sounds like significant draw-down on the battery. My routine is to turn refrigerator off when I leave (with doors cracked open and without anything in it that spoils or melts) then start it up as soon as I return, which could be a few days. I found a couple of thermometers at home to see starting temperature, will look again after it runs overnight, then switch thermometers to see if I get similar results. With this as a baseline, I can start following up on the many suggestions for sources of problems.
JRMunn