The fridge machinery on my B36(2002), was fitted several years ago as a condition of purchase from the previous owner. So far as I can tell, the machinery is nothing particularly special except that when the control is turned to maximum, it will freeze the contents of my fridge. However, the level of thermal insulation fitted in order for the fridge to retain its "cool" is insufficient for any length of time while dependent solely on the 12 volt domestic batteries. Up to now I've not got around to adding more insulation, despite fully intending to do so. Maybe it will get done over next winter, but access to the area outside of the cool box but behind the furniture panels is not easy, so at present I'm undecided on how to add thermal insulation.
So you might get away with an adjustment to your thermostat control, or you may need more powerful cooling machinery, but it is possible that you already have all you need to keep stuff frozen.
