I am a permanent plugged in, in a 21ft Class C Glendale. My fridge is a nice size, but I cant keep much in it, as even at a low setting on the dial, most everything freezes. Even in the door, my 2L jugs of milk are just above freezing, which is good, as I dont drink a lot of milk, and they keep longer.. The down side, is veggies, meat, etc. anything on the main shelf will freeze.. 

I had a dedicated 120v fridge with separate freezer which I use for stuff I dont want frozen. 

is my RV fridge on its way out, hence it being subzero cold. 

the Fridge is a NORCOLD model #875EG2

either the thermostat is stuck or gone bad or the sensor bulb has become dislodged from the evaporator or gone bad......both are easy fix!!!!

Check thermostat bulb to make sure it is mounted to the rear evaporator inside fridge.....do not take it off if you do not have to

take screwdriver and smack thermostat this should free up contact that is stuck....recheck fridge in 4 hours to see if temp is going up, if so thermostat was stuck and needs to be replaced.

if temp doesnt climb replace thermostat as soon as posible.

if when you smack it with screwdriver and it breaks.....replace right away!!!!! and dont smack things with screwdriver that hard again....

Note:....these instructions are given thinking you have a manual thermostat inside the fridge since your coach is an 88......if your temp is controlled outside the fridge you will need to start by changing the thermocouple sensor first and if that doesnt correct it the board would have to be changed