Issue fixed! After pulling the motor & fan out, we bench tested it with no result so ordered up a new motor from Winnebago. It also required an updated plugin that was different from the original and they knew that and sent it along. It came in 4 days. It was easy to plugin to the old wires and it worked right away, solving the problem. Heat, vent, and defrost now blow out of the correct vents. I didn't seem to generate cold air from the AC, but I'll deal with that issue later. It appears that somehow the AC unit has been disconnected and is not working. When set to AC it blows air through the vents just fine, so the blower is completely operational now.
The fan motor was easy to pull out. It is right in front of where the passenger puts their feet. I unscrewed a carpeted vent panel that covered it and then unscrewed about 6 screws in the housing for the motor and it pulls out easily for replacing.
Thanks for the help here.