"Low pressure" and "high pressure" is the part that confuses me. By the looks of it, the breakage would be on the high pressure side, assuming that the high pressure side is the part that runs back and forth in the grid array on the back of the fridge, and the low pressure side runs to the cavities that actually surround the food and do the real cooling. I figured the latter was the low pressure side because I've popped another fridge before with a screwdriver in a de-icing incident and the freon is just encapsulated in 1/16" plastic...not exactly capable of containing anything under "high pressure".
Hmmm...then what "freon" to use; R12, 134a, SP34e, R414? Probably the latter two because they are compatible with all freon types.