Re: How to determine which water pipe leads to the refrigerator.
Uh, guys, it is just as likely that there is a 1/2" supply directly behind the refrigerator. the lines you are speaking of are a "retrofit" answer in older homes. New(er ) homes have a dedicated line to the fridge, stubbed into the wall very similarly to how modern laundry hook-ups are, this is how it is done in my area at least. If this is the case, then there is no 1/4" line to find or follow. Dj1 is most correct, however, that some removal of drywall will be required to see which lines go where. I would suggest some exploratory surgery directly under the refrigerator wall. Make the cut large enough to get your head in there with a flashlight to look around. If it is possible to look in where the pipes are exposed in the basement, start with that.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!