I found a solution. This pic shows the snap on fridge vent under the bottom door.
The other is a plastic 1.5" railing baluster that I had from another project.

I cut the baluster to length, capped the ends and will double side tape it to the vent.

With the fridge bottom door closed...it can't be seen. (unless laying on the floor) The Roomba will not have enough room to wedge in.:)

http://forums.pelicanparts.com/uploa...1670268872.jpg