Hi:
I just had this problem  with my Roper refrigerator, Model RT14DKYBL00. I suspect it can happen with many refrigerator models with a freezer up top. I just fixed this probelm, here is how to proceed.
1. Shut refrigertaor down.
2. Remove all contents from freezer.
3. Looking staright ahead in freezer, the rear back panel, comes off. Find screws and remove panel.
4. There  also might be a floor panel. Remove that also.
5. At the rear of the  freezer, you will see a small narrow drain pan.
6. It is probably  covered with ice.
7. Look carefully and you  will find a drain on either the left side or right side of the drain pan. On the Roper it is on the  left side.
8. The sitting water has frozen, along with the drain. As the water slowly melts, it drips  into the refrigerator  via the  vents in the freezer, that lead to the refrigerator.
9. Pull the refrigerator  out. In the rear you will see a drain pan, that will have no water in it. You will see the small drain hose that goes back up to the  freezer.
10. Back in the  freezer, pour boiling water  into the  drain pan, until you melt all the  ice in the  pan in the  freezer and the  drain becomes unplugged. Took me about 1/2 hour.
Alternative is to let refrigerator sit  unplugged over night.
11. Once the drain becomes unplugged, the water will flow down the drain tube, and into the  drain pan in the rear of the refrigerator.
I am not sure what  caused this problem in the  first place, and how to avoid it happening again.
Good luck. Alec
                
 Alec
                
 October 2005