Water will not drain

check your drain hose and sink drain vent.

please check drain hose and sink drain vent (up near the faucet).

sounds like there is either a loose wire or bad switch on the water flow pump, not the drain pump What is the model number of the unit that your working on?

If you hear the drain motor running but water not draining then there appears to be a blockage in the drain sump or hose. Assuming your kitchen drain is clear you will have to check filters inside the dishwasher and worst the drain pump.
If you do not hear drain motor running then the drain motor needs to be checked.

Check part locations at this site
http://www.appliancepartspros.com/parts-for-whirlpool-du920pfgq3.html

drain pump gone replace.adrian,,,,,

As you say a clogged line or valve does not make sense.

Try running it without the heated drying and see if it empties or if the cancel button will work then.

The dishes should air dry quickly if you empty it and open the door.

It could be a defective thermostat allowing it to get too hot during the heat cycle

Sounds like a keypad malfunction or the control board has gone bad.

FYI, for anyone else with the same symptoms. I took mine apart and found that the seal on the motor shaft failed and over time corroded the motor shaft bearing causing it to failed. I ordered full motor assembly from the parts store.

The wash motor has probably froze up.

although hose is not clogged is it installed correctly?is there what they call a high loop installed under sink( loop up high as possible under sink to prevent both water siphoning out or returng back to machine after cycle complete. when you press the cancel button do you hear the water flowing freely into sink drain, if not sounds like you got somthin in hose or pump assy