When I was investigating the wiring diagram of my fridge freezer, I was also trying to find out if there is anything important in the divider between the fridge and freezer. Based on the diagrams I was confident that there was nothing in this area so I was free to drill holes.
I opted to put one hole in the front left and one in the back right.
I found the easiest way to cut the holes was with a hole saw, there was a thin plastic shell and then expanded foam. I first drilled down from the freezer until my hole saw bottomed out. I then used a standard drill bit to drill the pilot hole all the way through. I could then follow up with the hole saw from the bottom.
It turned out that even using a hole saw from both sides, I couldn’t get all the way through, so I then used a hacksaw blade and carefully cut out the “plug” of foam. Once I had cut all the way around, it was a simple case of pushing the plug out. The expanding foam is very messy and got everywhere.
Some of the parts also arrived today so I can start installing the fans when I have a spare moment. I’m really impressed, it took three days for my Temperature controller to come all the way from China. The Humidity sensor hasn’t arrived yet – must’ve been a different postage company.