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Tyler Z.
Tyler Z., Appliance Doc
Category: Appliance
Satisfied Customers: 56594
Experience:  7+ years being an appliance technician with factory training.
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what could be the cause of a lot of dirt in the dishwasher

Customer Question

what could be the cause of a lot of dirt in the dishwasher ( I clean periodically the filter and even I inspect the drain pump impeler). The drain pump impeler works since water is coming out.
Submitted: 10 months ago.
Category: Appliance
Expert:  Tyler Z. replied 10 months ago.
Hello, and thank you for using this service. I'll be helping you with your problem today.

So there isn't much that could just add a bunch of dirt into the dishwasher. Do make sure that your back flow preventer isn't damaged or broken. Below is a video that shows you how to clean out the drain and check the drain impeller, but it also shows you how to remove the back flow preventer. Other than that, you would just need to run the dishwasher through a cycle with Dishwasher Magic to clean the dishwasher out.

CLICK HERE to see video

Please remember to rate my service before you leave. If you have any other questions, please ask me – I’ll be happy to respond. You can continue asking follow-up questions until you have all the information you need even after rating my service. Thank you!
Customer: replied 10 months ago.

More details ...


 


This video has already been seen ... everything was just fine. Backflow preventer looks normal.


 


 


What could be the cause of a lot of dirt in the dishwasher ( I clean periodically the filter and even I inspect the drain pump impeler). The drain pump impeler works since water is coming out.


 


My wife is cleaning the dish every time before put in the dishwasher but still overtime there is some dirt residual every where in the dish washer (basket get dirty, filter section) We clean the filter and make sure nothing is obstruing the impeler very often.


 


Few months ago I make sure to have a high loop installation thinking this was potentially the issue .... but we still have the issue.


 


I dis-assemble the side panel to inspect the water inlet and the pressure switch. I found the water inlet pretty dirt try to clean by injecting water but still a little bit dirt... it seems there is a float or some kind of dispositive in the water inlet maybe it does not operate properly (the part still move however). Could a defective water inlet explain the issue ?

Expert:  Tyler Z. replied 10 months ago.
Nothing else can cause the issue---nothing. So if you're sure that the backflow preventer is working, then you just need to clean out the dishwasher properly with Dishwasher Magic. That is the only thing that can possibly fix your problem.
Customer: replied 10 months ago.


We will try Dishwasher Magic, but knowing that we already tried some product to clean dishwasher and also try a bit a Javex with water without any sucess I'm not very confident.


 


I have the Backflow preventer in my hand as I speak, What could be a defective Backflow Preventer after all this is only a piece of rubber !!!


 


Thanks,


 


Patrick

Expert:  Tyler Z. replied 10 months ago.
The rubber actually breaks sometimes. But other than that Javex is not the same.
Customer: replied 10 months ago.


Backflow preventer is not broken there is a rectangle section attached to a circular section. The joint between the circular and rectangular section is flimsy/thin but not broken.


 


So it seems my only potential fix is Dishwasher Magic ... :(


I'm very suspicious this will fix the issue .


 


We have tried Finish Dishwasher Cleaner ... without success the problem came back ....


 


 


Why the basket, filter, sump area would become so much dirt if we wash the dish before put in the dishwasher. This problem is there since a while and we are cleaning the dish .... but after a month or two there is a lot of dirt deposit. Is it not normal to toroughly clean a dishwasher each month... I doubt especially when you clean your dish ...


 


Could it be the temperature of the water not hot enough making not a good job to liquify the small amount of dirt (remember we clean the dish !!!).


 

Expert:  Tyler Z. replied 10 months ago.
I'm not saying the problem won't come back. You're supposed to wash the dishwasher out every few months with this product. But it very will might just be the change in detergents recently which is causing your build up. Detergents have removed phosphates due to regulation by the government in the last year or so. That causes grease and white residue build up to occur much easier that perviously. I recommend using an additive called "Finish Power Boost" (blue bottle with a red cap) which you add to your detergent.  In addition to that, be sure to use Jet Dry Turbo (not just normal Jet Dry) as your rinse agent. This will help your dishwasher from getting getting build up over time as well as clean the dishwashers better.

Whatever the case, the problem is NOT your dishwasher so you can stop looking for a problem on your dishwasher if the backflow preventer isn't broken.
Customer: replied 10 months ago.


I open the dishwasher in the middle of the wash cycle and the water temperature was not hot about 40C !!!!!


 


How can I make sure it is the heater itself or the heater realy that does not turn on the heater

Expert:  Tyler Z. replied 10 months ago.
So that would be a completely different issue and the dishes shouldn't even be coming out clean at all. To know if the heater is working, all you need to do is run the cycle and either the dishwasher won't finish at all and it runs for 3+ hours, or it will finish and when it's done there is no steam coming out when you open the door. If that's the case, you need a new control board---the heater does not fail on this model.
Customer: replied 10 months ago.


Could it be the thermistor ?


 


Changing the control board is pretty expensive I guess and could not find parts easily


 


Is the heater realy located inside the control board ?

Expert:  Tyler Z. replied 10 months ago.
The heater is not located inside the control board, but the heater and thermistor never fail on this unit. I have replaced 200+ control boards for the dishwasher not heating. I've never once replaced a heater and I replaced the thermistor one time, which did not fix the problem. Because it was a broken wire to the thermistor. Either way if the dishwasher isn't heating you will need to replace the control board.
Customer: replied 10 months ago.


That is strange we had a smoke failure 2 years ago and finally got free replacement of the control board since this was covered under a recall.


 


If it failing again then there is really a design flaw with the control board !!!


 


Do you know where I can get a control board innexpensive :)


 


 

Expert:  Tyler Z. replied 10 months ago.
So before the control board would catch on fire. The new control board still fail, but they do not catch on fire---that's the difference.

As for where you can get a new control board, it will never be inexpensive I'm afraid but Repairclinic.com or Appliancepartspros.com are generally the best options.

Customer: replied 10 months ago.

Before changing the control board which seems to be okay after visual inspection ( I could not see anything wrong like dark solder joint).


 


 


I want to make sure it is not the heater, I measure the heater resistance it is 11 ohms. Is this okay I have read somewhere else that heater shall be 30-50 ohms !!! Could you confirm or simply provide me heater spec.


 


If heater is okay then I want to check the NTC /thermostat


 


I just want to avoid buying a control board $150 if the problem is something else

Expert:  Tyler Z. replied 10 months ago.
The resistance should be 12 ohms, but either way, the heater is fine.
Customer: replied 10 months ago.

I have also check the thermal fuse and it is 0 ohms (good).


 


There is a flow switch in series I wonder what is the purpose of this switch ( it is normally open).


 


My next test is to test the signal on the big 2 pins connector (red wire) this signal is the 120VAC going to the fuse (which I previously tested .


I guess if there is no 120VAC on this connector pin then it means the control board is wrong .... In fact the relay on the control board is wrong.. I assume I could simply change the relay (de-solder it)


 


What about the NTC could it give false value to the control board in which case the control board could open the relay.


 


How can I make sure the NTC is okay ?

Expert:  Tyler Z. replied 10 months ago.
There is no point in making all these checks. I have told you from the beginning that the control board is bad. I would need to be there to call Bosch since you must be present in the house as an authorized servicer for them to walk me through wiring issues since they don't include wiring diagrams and wires actually change color from machine to machine. The NTC is NOT the problem as I have said before. You need to replace the control board. Could you de-solder the relay and do that? Possibly. It's not an authorized repair by Bosch so we have never done it. Will that fix the problem? Maybe. That's up to you if you want to try it or not, but the correct repair is to replace the control board.
Customer: replied 10 months ago.


I'm just a simple customer, the wiring diagram was in the dishwasher. A piece of paper folded in the base of the dishwasher. I have an Eng degree. but i do not know how works dishwasher. My biggest concern is spending $150 and still have the issue. This is why I'm doing all these checks before buying a new control board ....

Expert:  Tyler Z. replied 10 months ago.
OK then I would recommend ordering the part from Repairclinic.com where they allow you to return it if you're very worried about my diagnosis being correct.
Expert:  Tyler Z. replied 10 months ago.
Please understand that I won't want you to replace the wrong part either. I wouldn't tell you to replace a part unless I was confident that it needs to be replaced. And you need to replace the control board because it has failed if it's not heating.
Expert:  Tyler Z. replied 10 months ago.
I'm just following up to see how your appliance is doing since I haven't heard back from you and this question is still open. Is there anything else that I can help you with today?
Expert:  Tyler Z. replied 10 months ago.

Hello again, I'm following up to see how your appliance is doing since I haven't heard back from you and this question is still open. Is there anything else that I can help you with today?

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