4 replies to this topic

[TechnicianBrian]

Well I was having a good service day until I came across two dishwashers having similar problems.  Both were new and model #GU2400XTPB3.  The first complaint was when running in the normal wash mode, the washer runs until it gets to 63 minutes remaining and just keeps running without advancing.  Customer says they have given it up to 30 minutes and then stopped the cycle.  I figured must be a heating problem, and tested the heater circuit (it's good), and the thermistor (it to good).  On this one I am suspecting water temp as it was only 67 during the first fill when I arrived.   Later in the day went to another customer, this time the clean LED flashes 7 times indicating a heating problem.  But it all works in the diagnostics and functions electrically just fine.  At the very least, I can now check these out without refering to the tech sheet.  Anyone else run into this lately?  Thanks for any insight.  Brian

[Samurai Appliance Repair Man]

In the first job, tell the customer to run the water at the kitchen tap 'til it gets hot just before starting their dishwasher.

In the second one, has this dishwasher been serviced before for a heating element changeout?   The old NiFe heating elements are being replaced with NiMn elements, which have higher wattage.  The NiFe element is made of a Nickel/Iron alloy, which uses 400 Watts for drying.  The NiMn element is made of a Nickel/Manganese alloy, and uses 540 Watts for drying.

If the element has been changed, you need to make sure the electronic control has also been replaced to pulse the element to avoid overheating. The new element will be more angular in shape.

At what point in the cycle does the Clean light start flashing? 

[TechnicianBrian]

I did tell the first customer to do just that and explained the machine want 120 degree water to actually wash the dishes.  The second customer has not had an element change (it's the horseshoe shaped one) and  starts flashing about 15 minutes into the cycle (per the customer).  When running the diagnostics, it all works fine.  I did order a control board and thermistor thinking there may just be a control issue.  Thanks.

[Samurai Appliance Repair Man]

[user=46]TechnicianBrian[/user] wrote:

starts flashing about 15 minutes into the cycle (per the customer).  When running the diagnostics, it all works fine.  I did order a control board and thermistor thinking there may just be a control issue.  Thanks.

Could be a customer use issue!  I would verify the complaint myself before ordering the part.  But I understand that, as a Sears tech, you can't hang around that long and wait.

Let us know how this one turns out! 

[The Seven]

[user=46]TechnicianBrian[/user] wrote:

I figured must be a heating problem, and tested the heater circuit (it's good), and the thermistor (it to good).  On this one I am suspecting water temp as it was only 67 during the first fill when I arrived. 


Later in the day went to another customer, this time the clean LED flashes 7 times indicating a heating problem.  But it all works in the diagnostics and functions electrically just fine. 

It sounds that there is a "heating problem" in these two cases.

Have you measured the voltage across the heater terminals when it is supposed to be ON?
Is the heater power controlled by an relay on the circuit board?
Would it be possible to take photos on both sides of the control circuit board?

Some comments:
a) "works in the diagnostics" may mean the logic of control is mostly OK.
b) But the load current path may still have problems: most relays used in the circuit board have small tolerance to overload. The copper track for the load current on the board is also weak and may be heated up to cause melted soldering points at the terminals of the relays. In such case, you have an intermittent heater power.
c) It will work again when replaced with a new board. But the new board will develop fault soon because of (b).