FIXED DW80M9960G not cleaning right, but I don't think its a water wall issue

[Robert Hiebert]

Model Number

DW80M9960UG

Brand

Samsung

Age

1-5 years

We have a DW80M9960UG that we bought with a complete Samsung package in the fall of 2018, put into service in June of 2019. The package consisted of the dishwasher, French door refrigerator, gas range free standing range hood, clothes washer and dryer and a 50" TV. So far the washer, dryer, range and TV have been just fine. We have had problems with the range hood, refrigerator and dish washer, the dish washer being the most frustrating.

At first it worked beautifully, then about a year ago we started getting rejects in the lower rack. No trouble codes were set. After a bunch of research I determined it was the water wall reflector motor. I replaced the motor and all was good again until a few weeks ago. Now we would get rejects in the bottom cutlery section as well as some rejects in the upper rack. Still no trouble codes. I checked all the nozzles and filter. Everything was clean and rotated fine. I assumed it was the motor again, but now I'm not so sure.

I was able to get the service manual for the unit and came across this blog and the excellent thread on water wall motors. I was able to find instructions on how to do a diagnostic test, which I tried, and it passed completely. I was also able to use the butter knife trick to observe the water wall in action and it worked just fine. It moved from the back of the machine to the front and back again where it stopped at the home position. No muss, fuss or noises, so I'm wondering what else it could be.

Going over the parts diagram I see that the "Motion" assembly (DD97-00484A) has a cylindrical rotary valve that is gear driven. There is no part number for the valve or drive gear. With the reflector in the home position it looks like the port that feeds water to the upper and top nozzle is closed. I first assumed that this valve is driven by the reflector drive motor, but that doesn't appear to be the case. More studying of the parts diagrams brought up "Drive Motor" (DE31-10095B). My current theory is that if this valve is stuck in its present position the water flow will be blocked from going to the upper and top nozzles ands possibly not going to the right side of the water wall reflector, which might be the source of my problem. Is it possible that this motor drives the valve and if so when is it supposed to operate and how can it be checked?

 

[Jake]

I would help you but I have no experience or training working on Samsung dishwashers.

Hopefully another tech or member that's seen this problem and fixed it can shed some light on this issue.

 

[Robert Hiebert]

Update:
After more research and testing it's beginning to like an operator error thing. Everything tests fine, and the last few loads have come out squeaky clean.

I'm not completely clear on how the Zone Booster feature is supposed to work. If it is selected, does it limit the cleaning action to the left lower rack only, or does it add the extra cleaning to that section in addition to the selected cycle? The time remaining display would indicate that it is in addition to, but the rejects would indicate that it does not. The symptoms would indicate that if zone booster is selected then nothing else gets cleaned, or at least not cleaned well. We'll have to make sure we document just what settings we've used and if we get rejects , where they are located.

During the course of my research I checked the service manual to see what the symptoms would be if the distributor valve was not operating properly. In the troubleshooting section it mentions that the cam for the microswitch could be out of adjustment, but no place could I find what the proper adjustment was or how to change it. Can anyone shed some light on this?

 

[Robert Hiebert]

Update:
We still have a problem with rejects. The symptoms are similar to that of a water wall issue, but the water wall reflector is operating normally. Dishes are clean in the lower left hand side, with no rejects there, but there are rejects almost everywhere else. That indicates to me that the distributor valve is stuck in the "Zone Boost" position which only sends water to the lower left nozzles to be deflected by the water wall deflector.

I pulled the distributor motor assembly, which is the gear motor and limit switch, and bench tested them. Both operate normally. The valve itself is driven through a gear train on the output shaft of the motor. The cam is on the intermediate shaft that connects the motor to the first gear in the train. The first gear in the train is keyed to the intermediate shaft. The next gear is just an idler. The last gear is on the valve body itself. The valve turns in the same direction and speed as the gear motor shaft.

The valve has four passages, spaced 90 degrees apart. Position "A" sends water to the upper and top spray arms. Position "B" sends water to the spray arms and lower left nozzle. Position "C" sends water to the lower left nozzle only. Position "D" sends water to both left and right lower nozzles.

The cam is on the intermediate shaft and is indexed to it, but the indexing method allows about 80 degrees of movement either side of centre. The cam has 2 sharp lobes placed about 45 degrees apart and one long lobe of about 45 degrees duration. The centre line for the two sharp lobes and the centre line of the long lobe are approximately opposite each other.

I assume that the valve and limit cam must be indexed together to sent the correct signals to the controller but I don't see anything obvious on the gears to indicated this. The service manual mentions that a possible cause of improper operation could be the cam out of adjustment, but I don't see any reference of how to check this adjustment. Because I don't know what the controller expects to see and what it does when it sees it, I just made and educated guess and re-assembled it the way I thought it might go.

If anyone has any suggestions I'd sure like to hear them. In the mean time we'll run some loads through and see what happens. I'll report back on the results.

 

[Robert Hiebert]

Update:
So far it looks like my educated guess is working. The last load came out good everywhere. I reasoned that the only unique place on the cam that the microswitch roller could be positioned would be in the valley between the two pointed lobes. The most unique place for the distributor valve would be where you could see the port open to the upper and top spray arms before the spray manifold was installed. If this last load was just a one off I'll report back, but in teh mean time I'll call this one fixed.

 

[Jake]

Sounds good, Good job being persistent in fixing it, hopefully its fixed for good, fingers crossed.

Thanks for the updates you posted!

 

[Robert Hiebert]

You are welcome. I hope it might help someone else as Samsung Canada is impossible to deal with. That's a shame, because from my experience their appliances work well when they work, but when they break down you are on your own and parts are outrageously expensive if available at all.