Sub Zero 632 Fan dosen't quit running?

First of all our unit is 11 years old and when promted I have always vacuumed the condenser fins. The last time I cleaned it the message came back on a few days later, so I cleaned it a bit more and again it was good for a few days and then the message came back on. I then just reset it and it has been good now for about a week. Best I can tell the fan doesn't quit running and I assume that this is why I continue to get the "Vacuum Condenser" message (long run times?). The refer side stays at our normal 37 and the freezer side is good at
-1. There doesn't appear to be any condensation on the back wall either. Any adivce would be appreciated.
Thank You

Charlie
July 2009