A dead water dispenser is most often a control lock that got switched on, a new filter that isn't fully locked in, or a filter that's overdue and clogged. Look for a lock icon on the display first, then pull the filter out and try dispensing without it.
Check the lock, Sabbath mode and the paddle
Look at the dispenser panel for a padlock symbol or a lit Lock light. Whirlpool explains that the control lock only disables the dispenser pad and controls; the fridge, ice maker and light keep working. It's easy to switch on by accident, for example with a hand resting on the panel during cleaning. On many models you hold the Lock button for a few seconds to release it, and your owner's manual has the exact button and timing.
Sabbath mode does the same thing more quietly. Whirlpool notes that ice and water won't dispense while it's on, and that holding the Sabbath button for about three seconds usually turns it off, though the method varies by model. LG and Frigidaire show Sb on the display.
Check the selection, too. Many dispensers have separate Water, Cubed and Crushed buttons, and the paddle only does what's selected. Press a sturdy glass firmly against the paddle, not just lightly with a fingertip.
Pull the filter and test without it
If the problem started right after a filter change, the new cartridge probably isn't seated. Whirlpool's test is to remove the filter and try the dispenser. If water flows with the filter out, reinstall the filter until it clicks or the lock mark lines up, and try again.
If you just installed a filter, there's also trapped air to push out. iFixit suggests running about a gallon (3.8 l) through the dispenser. It will sputter and spit at first, which is normal.
A filter that's been in for a year or more can clog badly enough to stop flow. Whirlpool, Samsung and LG all say to replace the filter about every six months, or sooner if flow slows or the indicator comes on, and Sears gives the same six-month mark as a dispenser check. Our filter-change guide covers the swap.
Make sure water is getting to the fridge
If the ice maker is still making ice, the fridge is getting water and you can skip ahead. If both ice and water have stopped, check the supply. Follow the line behind the fridge to its shutoff valve, usually under the kitchen sink or in the basement below, and make sure it's fully open. Pull the fridge out carefully and look for a kink. Whirlpool warns that pushing the fridge too far back is a common way to pinch the line, and recommends 1/4 in (6.35 mm) soft copper or PEX tubing with a loop of slack behind the cabinet.
Pressure counts as well. Whirlpool specifies 30 to 120 psi (207 to 827 kPa) at the fridge connection, with the best performance between 40 and 80 psi. A reverse osmosis system under the sink can drop pressure enough to cause trouble, and Whirlpool wants 40 to 60 psi (275 to 414 kPa) at the inlet valve in that setup. LG flags low flow on some models with Er gF.
Close the shutoff valve feeding the refrigerator.
Put a towel down, disconnect the supply line from the back of the fridge and hold its end in a bucket.
Open the valve briefly. Strong flow means the house side is fine. A trickle or nothing means a closed valve, a clogged saddle valve or a plumbing problem.
Close the valve, reconnect the line snugly and check the fitting for drips before you push the fridge back.
Thaw a frozen water line
Water reaches the door through a thin tube, and on many fridges it passes through a storage tank or coil behind the crisper drawers first. If the fresh food side is set too cold, or cold air is blowing straight onto the tubing, the water in the line can freeze. A typical symptom is a dispenser that works for the first few seconds and then stops, or one that quit after you turned the temperature down.
Sears Home Services points out that a setting that's too cold or restricted airflow can freeze the tank or line. Raise the fresh food setting a step or two, and move food away from the vents near the tank.
Sears suggests thawing it with a hair dryer on a low heat setting. Unplug the fridge first as a precaution, keep the dryer moving so no plastic part gets hot, and keep its cord well away from any water on the floor. Plug the fridge back in once water runs again from the line.
Test the door switch
iFixit lists a faulty door switch among the causes of a dispenser that won't run. On models where the control won't dispense while it thinks a door is open, a sticking switch can stop it even with every door shut. If the dispenser stopped and you also get a door alarm with the doors closed, suspect the switch first.
iFixit describes a quick test. Open the door and find the plunger near the top of the frame. Press it and watch the interior light. If the light stays on, the switch is likely bad. Some fridges use a magnetic sensor instead of a plunger. On those, hold a small magnet against the top cover and see if the light goes out; if it stays on, the sensor is the likely suspect. Unplug the fridge before you pry out or replace a switch.
Check the water inlet valve and the door tubing
The water inlet valve is an electric valve at the lower back of the fridge. It opens when you press the paddle or when the ice maker calls for water. When it fails, you'll usually lose both water and ice. With the fridge unplugged and the water off, take off the rear lower panel and check that the wire connector on the valve is pushed fully on. A loose plug there is an easy fix.
If the connector is fine, the valve may be stuck. Sears notes that a technician confirms it with a live voltage check while the paddle is pressed, and says that test isn't safe for DIYers. With the fridge unplugged you can check the solenoid coil with a multimeter instead: Sears says a reading of infinite resistance means a bad valve. iFixit warns that a valve can also wear out mechanically and still read normal.
On many dispenser models the water tube and the door wiring run up through the top hinge of the dispenser door. iFixit points out that a hinge cover put back carelessly can pinch the tube, and that the wiring at the upper hinge gets flexed every time the door moves, which makes it a common failure point. If dispensing works only when you move the door, suspect that wiring.
When it's the dispenser switch or control board
If water reaches the valve, the valve is good, and nothing comes out, the trouble is in the dispenser's own controls. A small microswitch behind the paddle tells the board you're pressing it, and a dispenser control board runs the valve. iFixit's rule of thumb helps here: if ice still dispenses and the controls respond, the dispenser board is unlikely to be the problem. These parts sit behind the door panel and are tested with the power on, so this is technician territory for most people.
When to call a professional
Call a technician if water reaches the back of the fridge but still won't dispense after you've checked the filter, lock and door switch. Intermittent dispensing that changes when the door moves, or a valve that tests fine but won't open, needs live testing by a pro.