I just completely rebuilt my 25 yr old refrigeration
. The original system used two seafrost holding plates with a hole for a damper in the bottom of a plywood
divider between fridge and freezer and a corresponfing gap at the top. Holding plates developed a leak so I made two new ones added insulation
to the divider and closed the gap at the top. I installed a fan and thermostat to blow on one plate and the air is returned back to the fridge. It is a fairly large system but running off a BD 5 air cooled unit. The performance is markedly better with the fan. I used to have things freeze in the bottom of the fridge. Now both temps are fairly constant, freezer is at -12C and fridge about 6 C. Amp draw is within capacity of solar panels
bank so all runs when I leave the boat for a week or two.
I am in Talagi, Langkawi if you want to discuss more.