Hi, I am lucky enough to have a Samsung S RS 2028CSS showing the same symptoms many have described.
Fridge pulls down to set temp in 3 - 4 hours but then warms up. I have tried the diagnostic test - I pressed Quick freeze and Vacation for 8 secs as described on the back of the unit. Everything on the display flashes then a beep then blank display for about 15 secs then back to normal. If I switch off, switch on 3 is displayed on the fridge side before normal display on fridge and freezer.
An engineer called and said it must be the control PCB.
That sounds expensive. Any thoughts what the lack of error code means?