Product review (5 stars): This Fixed My Water Flow Problem.
After changing the filter, I had no water flow at my water dispenser in the fridge door.  There is a small valve inside this part that opens when a filter (or the bypass) is installed.  That little valve malfunctioned on my original part.  I proved it was bad by disconnecting the output hose at the back of the fridge and verifying the lack of water flow.  There are other causes that can stop water flow, so be sure you verify which part is bad.

I ordered, received, and replace this part.  Everything works fine now.  The installation is not complicated.  The tools needed are a wrench and a nut driver.