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Hi, Bill...............this may be due to the 12 VDC side not connected up to the batteries. Check the disconnect switch. The lights and fridge should be 12 VDC controlled, even when you try the fridge on AC mode. It may be the batteries or the converter or inverter/charger.........depending on which you have isn't up to speed. Check the water in the batteries first and the connections to be sure that they are not dirty with corrosion. Have them load tested at least once a year. IF they are 3 years old or more, chances are pretty good they may need replacing Hope that proves helpful here. If you need more, please get back to me and we can look further. A 12 VDC test light or small digital multimeter would be helpful for diagnosis.
I will make the phone call offer for you...........