has anyone tried mounting it against the outside opening so the fan only draws air from the outside?
I'm in the process of doing this myself. For now, I bought a small 110V muffin fan that I'm just placing (not mounting yet) just inside the fridge panel. Will see how much it affects temperatures when it gets hot out.
For fun, I turned it on while starting up my fridge.. Was 50* outside, and it seems that it actually slowed down the fridge cooling. When I turned off the fan, it started cooling faster. I guess it requires some heat to operate. I'll test again when the temperatures rise.