Finished repairing my RS21DCNS about 15 mins ago.
Before it started doing the same as yours I noticed a strange noise every now and then that stopped when I opened the fridge door. I noticed the noise came from behind the panel marked "Dual Cooling."
Having an electronics background I thought I'd check it out. Anyway, it was a build up of ice stopping the rotation of the cooling fan under the panel mentioned above. I removed the panel, cleared the ice, put it all back together again and now it’s at a nice cool 3 degrees.
Email me and I’ll send instructions to carry out the repair. I suggest if you’re not qualified, don’t attempt it. However an electrician or some other kind of service personnel should be able to do it.
rogerc2008@fastmail.fm
Roger C, August 2008