Your water line could be frozen in the door. You can disconnect the line under the unit before it goes into the door at the bottom hinge. Push the dispenser button and see if it comes out there. If it does leave the door open till it thaws.

You can also check the water flow out of the valve by disconnecting the line to the water dispenser at the water inlet valve on the back where the water supply comes in and try the dispenser.

I have a Maytag side by side refrigerator model number mzd2665hes. The water dispenser quit working. The filter has been replaced. Water stopped gradually, but now only trickles. Refrigerator is 3 yrs old. Initially when the problem began, I could hear the solenoid picking up dropping out and adjusting the water valve pressure from the wall seemed to have fixed it. Now, you can hear the click of the switch when depressed and water just trickles out very slowly. Ice works fine. Water valve is open all the way. Im not sure if the problem is a faulty solenoid switch or if the line is frozen. Any help or advise welcomed. :)