fridge doesn't get cold enough
I have a norcold fridge model N621 that gets cold in fridge and freezer, but not cold enough. I am unable to adjust the temp from the front panel. It is set at 1, and if press the temp button, nothing happens. If I press and hold it, the LED display goes to "8", which i believe is a code of some kind. I suspect there is a problem with the front control panel, but would like confirmation. When I unplug the thermistor, there is no change in temperature. the part number on the thetford website seems to indicate this control panel is part number 633292 since my seriel number is 1294864, but I am not confident I am reading it right. Also, is there an upgrade option recommended to replace this part?