I was doing a final wax and cleaning on my Lil Bigfoot
today and had the upper refer vent off
I had a problem with the refer cooling down enough so I added a baffle that forces all of the air over the condensor coils.
It was easy and cheap.
You can see the baffle in the attached pic.
I screwed a 1"x1" scrap of wood just below the bottom of the vent, hot glued a scrap of plywood to the the 1x that was as wide as the back of the cabinet and deep enough to almost touch the upper coil.
I sealed the ends with foam.
Now if I don't watch it I freeze the food in the refer.
I went fishing on the Kern for a couple of days and the temp was in the high 90s.
It's an easy, cheap and quick fix.
Try it before you add fans.