If the fridge has a finned radiator on the back then it is most likely OK to drill the sides but just to be sure you can feel the sides when it has been running a while and if they get HOT then you can not drill in the sides, otherwise it should be OK to drill in the sides if the radiator (condenser) is on the back side. Unless the door has an ice and water fountain you can drill with no worry. Use a hole saw, they work better.
Fermentor 1: Bill's House Ale II, Fermentor 2: German Helles, Fermentor 3: Bill's Schworzbier (Black Bier)
Tap 1: Bill's House Ale II, Tap 2: German Hefewizen, Tap 3: Nut Brown Ale
Future Brews: Stone IPA Clone, Blonde Ale, Budvar Clone, Newcastle Clone
New toy: Blichmann 27 gallon fermentor
“If you find yourself in a hole, the first thing to do is stop digging”
“Good judgment comes from experience, and a lotta that comes from bad judgment”