Maytag dishwasher detergent cup doesn't open

[slantsixdan]

Maytag dishwasher model WC202, serial 645309 RA.

Twice out of the last four loads, the detergent cup cover has not opened. When I go to unstack the dishwasher, I find the cover still over the main cup, having failed to rotate to the open position. I'm not doing anything differently than I always have as far as brand and amount of detergent powder. Before I disassemble the door to try and see what's broken, any pointers?

[Samurai Appliance Repair Man]

Usually, this is the bimetal that's starting to go flakey:

http://www.repairclinic.com/referral.asp?R=154&N=1331

And just hope that's all it is. Parts are starting to go NLA on this machine. The detergent cup assembly is NLA, for example.

Here's a breakdown diagram of the door section, including the detergent door assembly.

What I would do is see if the timer is sending 120v to the bimetal when the cycle begins (after the initial pumpout). If so, then the replace the bimetal. If the voltage from the timer is flakey or not always there, then the timer is bad.

[slantsixdan]

[user=1]Samurai Appliance Repair Man[/user] wrote:

Parts are starting to go NLA on this machine. The detergent cup assembly is NLA, for example.

For US models, yes. Looks like the different detergent cup used on Canuckistan models (why???) like mine are still available.

What I would do is see if the timer is sending 120v to the bimetal when the cycle begins (after the initial pumpout).

Two wires connect to the bimetal, a blue and a white/orange. With those wires disconnected, I see between 11 and 20 VAC across them whenever the machine is in a drain, wash or rinse mode. When it's in a dead zone between modes on the timer, or when it's filling, voltage drops to between 1 and 2. There is a brief period of 120 VAC across these two wires in the portion of the wash cycle that occurs about 3/8" after "Light Wash", i.e., the part just before the rinse.

It seems this machine feeds the main motor through the bimetal in some modes, notably during that "light wash" portion of the wash cycle. Seems odd to me, but maybe not to you.

If the voltage from the timer is flaky or not always there, then the timer is bad.

1. I'm guessing my description points to a faulty timer. Do you concur?

2. Correct timer for WC202/WU202 is a 9-01980. I have access to a good used 2-01992, from a slightly fancier WC502/WU502. Physical dimensions of the two timers are identical. The WC502 used a 3-button control switch not found on the WC202, don't know what the 3 options are.

The 2-01992 has a few terminals that don't exist on the 2-01980, and some of the terminals with like numbers are differently placed on the two timers. Can you say if the 2-01992 would work in my application if I connected the machine's wires to the same-number terminals, jumped together those terminals on the 2-01992 that are jumped on the 2-01980, and left alone the extra terminals on the 2-01992?

[Samurai Appliance Repair Man]

Your test, as described, is inconclusive because it sounds like you measured the voltage drop across the bimetal. What you really want to do here is measure the voltage at the bimetal with respect to neutral-- that means one probe on a bimetal terminal and the other on a neutral point (or a chassis ground point, assuming neutral and ground are at nearly the same potential, which they should be in a properly wired circuit). If you get a valid voltage supply to the bimetal (nominally 120v) then replace the bimetal.

[slantsixdan]

[user=1]Samurai Appliance Repair Man[/user] wrote:

Your test, as described, is inconclusive because it sounds like you measured the voltage drop across the bimetal

Don't think that's what I did, for I disconnected the wires from the bimetal before measuring the voltage on the wires.

What you really want to do here is measure the voltage at the bimetal with respect to neutral-- that means one probe on a bimetal terminal and the other on a neutral point

I'll try that tonight and report back, thanks.

[slantsixdan]

[user=1]Samurai Appliance Repair Man[/user] wrote:

assuming neutral and ground are at nearly the same potential, which they should be in a properly wired circuit

I found 70 to 90 VAC across bimetal and chassis ground, rock-steady 120VAC across bimetal and neutral. Tilt!

The previous owner of this unit hacked the ground pin off the line cord plug. I installed a new plug and got solid 120VAC across bimetal and chassis ground.

Three out of three times now, the detergent cup has opened right on cue. I can almost understand how floating grounds could cause flaky behaviour here; what doesn't compute for me is why the unit worked fine for years without the ground pin and just suddenly decided to require a proper ground.

(I'm also really pushing my luck, as I haven't yet reinstalled the door face panel, and I know the dishwasher reads this forum...)

[Samurai Appliance Repair Man]

Great troubleshooting, dude!

You have tasted the cup of victory. :pint:

Thanks for letting me know how it turned out.