First, insulation and a good door seal will be the major factor for power consumption
. 99% of the factory ice boxes have little to no insulation. Having just built a new box in my boat I have some suggestions.
I cut, smashed and ripped the old box out, including a good bit of the cabinet that held it. To keep the original look and function I saved the pieces of the old box, insulated the cabinet where it had been, made the box smaller, glassed it back together, reinstalled the box into the cabinet and put the cabinets back together. It was a HUGE project
. 20/20 hindsight it would have been much less work if I had kept the original box and lined it with new insulation and then built a new liner. Would have been a slightly smaller box but probably still large enough.
For new liner, forget stainless. Too expensive and too hard to work. You can buy 4X8 sheets
of fiberglass panel at Home Depot or Lowes. Insulate the box, cut pieces from the 4X8 to fit the new walls, sides, etc (it is flexible so will probably fit into the opening) and glue them to the foam walls. This is one place where 5200 wil work but epoxy
also. Don't use most glues as the solvent in the glue will dissolve the blue foam. Use thickened epoxy
to make fillets to fill and seal the seams.
I'm guessing that this unit may use an older type of Freon that is now regulated as an ozone depleter. If the unit is still sealed and functional then it might be worth keeping. Have you tried turning it on to see if it cools at all?
My box is about 9 cu ft after insulating which includes a 1.5 cu ft freezer
section. I went with the larger BD50 compressor
and after cooling
down use less than 50 amp hours/day in August in Florida
with temps >90F. Winter in FL used half that. So far a single
, low end, 135 Watt solar
panel has been keeping the fridge going with power to spare.