When I drilled the holes in my fridge I found a diagram of the freon lines & electrical stuck under the front of the fridge. Showed me exactly where the lines were routed. Then as an additional precaution I drilled a small hole on the inside and used an ice pick to probe around. Then a little bigger hole, moved the insulation out of the way and took a visual. Then I drilled the final hole with a step bit. I used rubber grommets (inside & out) to protect the CO2 line. Cheers!!!