Thanks Carman850, but....
as I said in my original post, this problem does not appear to be related to the Climate Control System blower fan that your URL link refers to. The problem occurs when the Climate Control System is in the OFF position. I even tried turning the CCS on and off when the problem occurs. Doing this has no affect on the problem, so that leads me to believe that the blower fan is not where the noise is coming from.
Still looking for help.....