Shut off the water valve that controls the water flow from the water dispenser and ice maker. You'll have to consult your owner's manual to see how to disconnect the ice maker line. Once the line is disconnected, pour 3-4 cups of vinegar with a small funnel into the line and let it soak for 5-10 minutes, clipping shut the open end of the line to avoid the vinegar from draining out. Rinse out the line with clean water before reconnecting the dispenser and ice maker.