Today I decided on how I was going to add a screen to the refrigerator vent opening.
I took some 1x4 I had laying around from the shed I built last summer and ripped some pieces to make a frame. Basically 3/4 x 1" or so and another piece that was about 3/4 x 3/4" and nailed them together then mitered the corners at 45 degrees.
I attached them inside the opening for the vent with enough room to close the original vent shield. Caulked them and then painted the caulk black.
I measured the inside and bought some screen from Home Depot and the corners and stuff to hold the screen (rubber string) and make a screen to fit.
I ended up just screwing the screen in - I figured it would hold better and if I ever need to get in there its just 6 screws.