I had the same problem, the fridge never got below 45 degrees the first time I used the trailer. There is a sensor called a thermistor attached to the fins in the fridge, if it isn't working the fridge won't cool. I replaced mine with an adjustable sensor, and it kept the fridge in the low 30's until I tried to adjust it up a little, then it dropped into the 20's and froze everything. Hopefully I can get the adjustment right but the point is do a little reading on thermistors; you might just need to move the sensor up or down to get the correct temp but it is fairly inexpensive and easy to replace.