1986 30P Avion trailer Electrical Problem

That model number for the fridge was on the outside access cover. The fridge has an auto light on the outside and a gas push button to turn the propane setting on or off. It also has a climate control switch on the inside upper door for the freezer. No voltage reading on the 12 volt wires that go to the fridge circuit board. the 30 amp fuse that keeps blowing is behind the monitor panel above the fridge. I read 13.2 volts at the fuse location. My fridge no longer works or the 12 volt stereo and the 30 amp fuse blows immediately when I replace it. There is an analog ampmeter on the same circuit by that fuse that has never worked. I wonder if that is bad and is shorted out.