Appliance Repair Blog

Thoughts and commentary about appliance repair topics including common failures and repairs, plus links to frequently used parts, industry news, along with information to help you better understand your appliances. Resources available for the technical professional and the do-it-yourselfer.

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Here is another post from the mailbag where a visitor to my site by the name of Nickole was in search of some information to get her dishwasher working properly again. Here she described what was going on.

I was reading your post Frigidaire Dishwasher keeps Running and will not finish the cycle. Mine is doing this too. In the answer you stated the problem was the temperature boost thermostat. How will I know if its the thermostat OR the heating element? How can I know the difference in these two problems? Should I just replace them both? My model number is FDB635RBS0icon Thanks!


Well lets not replace them both. Instead, lets find out which has failed.



As I described in the previous post, this dishwasher uses a normally open bi-metal thermostat to determine when the water temperature has reached the preset limit. This thermostat only comes into play when the temperature boost option has been selected which will stop the mechanical timer at pre-set points called thermal holds, and turn on the heating element. As the wash pump and element are operating, the water temperature within the tub will increase until the cut-in temperature of the thermostat has been reached. This causes the thermostat contacts to close and allows the timer to continue on with the cycle.

I suggested Nickole check the heater by advancing the timer to the dry cycle and then to start a wash cycle with the temp boost option off. She replied with the following information.

The heating element heated up, so that is working.

The other night, I started the dishwasher and when I woke up the next morning the washer was still running. It seems that it only gets stuck when the "heating delay" light comes on. It will move along, if I move it along, but once that "heating delay" light comes on, it gets stuck again.


With this bit of information, I suggested she run a wash cycle with the temp boost option turned off. By doing this, the dishwasher will not pause to heat water and should continue to run if everything else is operational. The fact the timer will advance if pushed along indicates the timer is working fine and just sticks at the thermal holds. She followed my suggestions and then got back to me with this bit of good news.

You are right! Thank you, the dishwasher works when I turn off the high temp rinse.
We will replace the thermostat.
Thank you so much for answering these questions. I appreciate it so much!


Looks like a new temperature boost thermostat icon will do the trick to get this dishwasher running properly again. Thanks for visiting Nickole, I am glad I could help.

5 comments:

Anonymous said...

This post was really helpful... I was on the right track but not certain. Then I read this post, and now I am certain that the thermostat is my problem as well.

Jack said...

I have the same symptoms as Nicole but I replaced the thermostat which metered out as open, but I replaced it and the dishwasher still stops at the thermal hold. If I move it along manually it will finish the cycle.
The appliance repair guy I called says there are 2 thermostats. Is that true? and could that be the problem?
Thanks!
JTH

TechnicianBrian said...

Jack, there are two thermostats. One is normally open and the other normally closed. They both look alike, but are not interchangeable. The one you are looking for is connected to the orange and yellow/black wires. That one is normally open, and then closes once the water temperature get high enough, thus the thermal hold on the timer. The other one is a safety thermostat for the element. If it reads as open, it has failed and thus the element never will turn on. Both must be working correctly or the timer will never advance from the thermal hold. Hope this helps.

Jack said...

Hi Brian
Thanks for your input. Looks like I repaced the wrong thermostat. That was the only one I could see under there. Do you know where the element's thermostat is in relation to the first with the yellow/black and orange connection?
Thanks
jack

TechnicianBrian said...

Hey Jack, The other thermostat is also under the tub and looks like the one you replaced. Look for two other wires, likly red ones, that connect just like the orange and yellow/black.

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