Best way to clean fridge ice maker lines?

I've had better luck using a mix of equal parts white vinegar and water pushed through the lines with a turkey baster or syringe rather than trying to flush them with just water. The vinegar breaks down mineral buildup that plain water misses, and it's cheap enough that you won't worry about waste.

If the lines are really clogged, you might need to disconnect them (most ice makers have a clip or nut at the connection point) and soak the tubing in vinegar for an hour or two before flushing. Just make sure to run fresh water through afterward so you're not tasting vinegar in your ice cubes.

the vinegar-and-water approach definitely works, but here's what actually saves you time: disconnect the ice maker entirely before you start, not after. sounds simple but most people try flushing lines while everything's still hooked up, which just pushes gunk back into the system. once it's disconnected, you can flush with way more pressure without worrying about damaging sensors or valves. use hot vinegar solution (warm it up a bit) instead of room temp - it cuts through mineral deposits way faster, especially if your water is hard like mine is.

the turkey baster method from the other answer is solid for gentle work, but here's the hack: get a cheap aquarium air pump from a pet store for like 15 bucks. hook it up to push air through the lines after you've run the vinegar solution through. the air bubbles break up stubborn buildup that just sitting in vinegar won't touch. takes maybe 20 minutes total and you won't need to replace lines prematurely. also, if your lines are really gunked, don't be shy about using distilled water for the final flush - tap water just redeposits minerals right back in there. after you reconnect everything, run it for a few cycles and toss the first batch of ice cubes, just in case any vinegar taste lingers.