The water valve in a refrigerator is a major component of the automatic ice maker system. If the cubes become too small or become a solid chunk, odds are the water valve isn't working right. If you need a Water Valve for Whirlpool 4318046, this OEM-equivalent from Exact Replacement Parts should work.
Make sure this fits by entering your model number.
Manufacturer model # 4318046
Genuine Replacement Part