i would call ally hes a samsung engineer - can give free advice and sells the parts to repair
tel 07407 734 204
his ebay listing give you a bit more info
rs21/srs models Item number: 280739526146
rsh1 models Item number: 280645411839
hes just helped us fix our rs21 model that had same issue so i can recommend no probs
gregor, July 2012
most of these american spec fridges give the same trouble it is down to not defrosting usually caused by defrost element failure, defrost your fridge fully and if it works fine for a week or so i would suspect element failure
keymatic, July 2012
edit
I can answer this question...
the temp on my american fridge will not go below 14oC, the freezer is ok?