Check the
wiring to the unit. Waeco suggests
wiring direct from the
battery bank, not through the main panel, with a 10 amp fuse in the line. Waeco also suggests larger wire size, 10 guage for up to a 13 foot run, larger for longer runs. Check with a multimeter that, when the fridge is running on DC, it is getting at least 12 volts and drawing about 5 or 6 amps.