Our 1st trailer had a 3 way power fridge also. It was a smaller 3 cu ft I think
with one door. Freezer was just a small compartment in the top of the fresh
food area with a plastic door. Just room for a couple of ice trays.
I'm going way back in the old memory banks here but I believe the manual
said specifically that DC mode was only to be used while the tow vehicle
was running. I assume they meant that your tow vehicle was connected
to the trailer 12v supply/battery via your trailer plug.
It also said that DC mode would not keep food as cold as either LP or 120v
The high amps load coupled with dismal cooling is one reason you hardly
see 3 way power on refrigerators today. I suppose they were a tad
more expensive as well.
Low battery voltage upon arrival at our destination coupled with luke
warm beer is why we stopped using the DC mode.
On AC or LP that little box would freeze our lettuce on a regular basis
but the beer was cold!