Mailbag: Whirlpool Dishwasher Detergent Door Won’t Open

michelle clark wrote:

Hello, Samuri…
Maybe you can help me with this one.  My Whirlpool dishwasher is only 3 years old, but the soap dispenser does not open.  I opened the unit up, and replaced the wax motor (part number 3374501).  I was quite proud of myself because it worked… the first time.  However, it did not work the second, third, ect.  Now, I am a little disappointed, but ready to try again.  I am an ex Navy ET, but don’t know a thing about dishwashers.  The model number is DU920PFGQ4.  I have a copy of the technician schematic, and there doesn’t seem to be any other problems with the dishwasher. 
Thanks for your time,
Shelly Clark

Check the simple stuff first: make sure your dishwasher racks aren’t interfering with the detergent door. This will happen if the rack is put in backwards or isn’t seated properly. Also, if the silverware rack has fallen off recently and you re-attached it, make sure you didn’t position it right in front of the detergent dispenser.

Ok, with the simple stuff out of the way, let’s get into the gory techie stuff. Start by checking the wax motors with your ohm meter, should get 600-1800 ohms. If you do, then the wax motors are good and the problem is that you’re losing voltage to them. Key components to check are the thermal cutoff (normally closed) and the electronic control. Easiest to do a live test and trace the voltage back until you find it. You’ll need the wiring diagram/tech sheet for this. The wiring diagram is either in the kickplate (on bottom) or in the control console but you can borrow my copy in case you can’t find yours–just be sure to return it!

Referring to the wiring diagram, if you measure 120v on P8 of the electronic control but it’s not making it out P9, then the electronic control is bad. Conversely, if you do measure 120v on P2-3 or P2-4 of the electronic control, then the electronic control is bad. The tech sheet also shows how to initiate the rapid advance service feature and diagnostic cycles. This can greatly facilitate troubleshooting by advancing the dishwasher to only run at the part of the cycle where the detergent door opens.


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