Well Jim@HiTek, looks like you nailed the problem with your suggestion about the battery issue. I have 2 6 volt batteries set up for 12 volt. There was corrosion at the connections. Cleaned the cable ends with sand paper then plugged the converter into my house outlet overnight. Power off on my 30 amp cord. This morning I turn on the 30 amp and all back to normal.
The fridge still runs only on gas, so I think I do have a bad electric heating element. But I can live with it running on propane until I can afford to fix it.
Heater is silent too!
Thanks for your help!