The 3 most common part(s) or condition(s) which cause the symptom Refrigerator water dispenser not working are listed below starting with the most likely. Check or test each item and watch any available videos.
If the refrigerator water dispenser is not working the water supply tube in the door may be frozen. This will be difficult to track down. Look for a connection point at the bottom or top of the door, try removing the hose and blowing air through it and out the dispenser. If air passes through, it's not frozen. If not, thaw it out. and determine where it froze in the door. Most doors are foamed in with a sleeve the water line goes thru to the dispenser. The freezer temp should be kept from 0 to 10 degrees Fahrenheit. If it is too cold the water line in the door may freeze.
If the water dispenser is not working the water pressure from the house might be too low. Water inlet valves require a minimum of 20 psi to function properly.
RepairClinic Item # 3071
If the refrigerator water dispenser is not working, the door switch might be defective. When the freezer door is opened the freezer door switch does two things, it turns on the light in the freezer and turns off the ice and water dispenser. If the door switch fails the dispenser will not turn on. The switch can be checked for continuity with an Ohm meter. If it doesn’t have continuity it should be replaced.