I rang the fridge manufacturers and arranged to visit a repair centre in Clayton at one o'clock.
We got a bit lost in the city trying to avoid the toll tunnel but a bit of intuitive navigation got us back on track and we arrived with time to spare.
The diagnosis was a blocked gas jet. Unfortunately the tech didn't test the fridge on gas first so it's a bit hard to see if the repair made any difference. I paid a sizeable bill and said I'd test the unit overnight.
We had trouble finding somewhere to spend the night because the place we had stayed at last time we were here had disappeared. A bit of telephone detective work found a suitable place in Dandenong. We stopped for a late lunch at Macas and we arrived at the park at about four.
It's hard to tell what is happening in the fridge because the weather had turned hot. When we eventually settled in to the caravan park, the freezer had gone up to 2°C and the fridge to 9°C so I terminated the test and switched to mains power in the hope that the temperatures would come down again as they had last night. They came down a bit but not a lot. Overnight I put it back on gas.