Our brand new Whirlpool WRS321SDHZ08 (21.4 cu ft side by side) has exactly the same problems. The coil has 12 turns and is 8.5 in diameter. I was told that the 5/16" tubing has 1/4" diameter. With an extra turn for the tubing leads to the coil, I get a capacity of 9.4 oz. The air temp next to the coil is 36°. Service tech and I agreed on water temp, never much below 60° and averaged 65° over several portions in a paper cup (which has little heat capacity). Before tech and I measured it, the water had not been used for 10 hours. Previous Whirlpool top-freezer with internal water dispenser did provide a first glass of really cold water but subsequent glasses were not as cold.