NON-RESETTABLE BI-METAL Fuse

[BrokenDW]

Hello,

I am looking for information on exactly what a, "NON-RESETTABLE BI-METAL fuse" is.

I can say I have 5 identical fuses and at room temperature one of the fuses shows open loop for ohms

The other 4 show about 0.3 ohms, so I am assuming these are good but I could be wrong. I am thinking when these heat up to about 160F maybe the 2 metals should come close to one another and when they do, it will prevent voltage from passing thru ( the fuse tripped ).

I am afraid to heat these up for that reason to test if this is True or False because they are labeled as, "NON-RESETTABLE".

So I have a dishwasher and right before the dry cycle the machine always loses power. Then after say 15 minutes the indicators are restored and the Start light blinks. So putting aside there may be a heating element issue, it seems to me the, "NON-RESETTABLE BI-METAL" fuse is actually a "RESETTABLE BI-METAL fuse"?

Or this fuse is not causing the shutdown in the first place.  Does anyone have any ideas on this issue?

Thanks,

Rick

 

 

 

[BrokenDW]

I see no replies yet, but it just occurred to me, when the dishwasher shuts down, unplug it then take out the bimetal fuse from the control board ( might be hot ) and test for ohms. If it still reads about 0.3 ohms then something else is causing the power going off.

Rick

[Budget Appliance Repair]

A non-resetable thermal cutout or cutoff will not usually act that way.

For an intermittent problem like you are describing especially being it starts at or near the heating cycle, I would be looking at the connections inside the terminal box where the power cord or hardwire is attached to the dishwasher.

Good chance you are going to find a loose and/or burnt connection at the incoming power cord or hard wire from the house where it it joined to the dishwasher in the junction box of the dishwasher.

[BrokenDW]

Hi William,

Ironically 2 days ago I replaced the power setup I had with a, "GE 6-ft 3-Prong Black Dishwasher Appliance Power Cord". I was actually thinking that too. Maybe the wire twists are not tight, however just 30 minutes ago it did the same thing again.

This time however I wanted to see exactly what was going on with the bimetal thermal fuse, so I waited for the shutdown ( happens all the time ) and when it did, I unplugged the power cord from the outlet and removed the bimetal fuse. I did all of this in under in under 5 minutes ( the state of this fuse 5 mins after I assume is the same as t=0 sec. ). In any case I got my first reading at it was 0.1 ohms as time went on the fuse eventually went back closer to 0.3 ohms. I then put everything back together and restarted the dishwasher and from here on out it ( after pressing on the blinking start button )it  always successfully completes the heated dry portion and then the indicator moves to clean. And it it done. 

I was wondering if this problem is not solvable, meaning it is a software bug.

For example if some code ( written into the eprom ) has if bimetal fuse has and ohm value of less than 0.2 ohms trigger a shutdown )?

For now there is not much I can do, but continue troubleshooting things I can see. 

The heating element has 18 ohms when isolated from the unit. But maybe something is wrong here when it is heated. I have no idea on this.

Yesterday I checked the pins on the vent fan fan and I forget the ohm values but they looked good on P1 and P5. But the vent itself has a plunger mechanism that pushes forward when the dry cycle is about to begin. I have no idea if this plunger fully extends. Or when the wash cycle begins the arm fully extends ( has a rubber boot ) and when I find it on inspection it is NOT fully extended. Maybe the vent mechanism is the culprit. 

But this is where it is at right now. After checking on the dishwasher just now I have 4 indicators lit up and this is normal and soon it will go to the clean indicator indicating success. 

Also I have run the diagnostics mode and compared it against a whirlpool diag. chart and everything seems to run fine in diag. mode.

Rick

 

 

 

 

[Terry Carmen]

On 12/14/2021 at 10:33 AM, BrokenDW said:

I am looking for information on exactly what a, "NON-RESETTABLE BI-METAL fuse" is.

It's kind of a bad description. 

A bimetal thermostat contains a piece of metal that bends and opens a contact at some temperature and then closes again at some lower temperature.

"nonresetable" means that it won't close again at any temperature it's likely to encounter, so once it opens it stays open, but the technology is the same as the operating thermostat in a dryer.

A real thermal fuse, like the one hiding in the wiring harness of a lot of icemakers contains a small blob of metal that melts at some temperature and will never reset.

You definitively don't want to test any of these by heating them up. It's like testing matches. Once you blow it, it's done.

What's the model number? Different brands have different common problems.

[BrokenDW]

Hi Terry,

The part is:

Part #W10258275

I am sending the spec sheet portion that shows it referenced.

Also a colleague of mine said to discharge the capacitors on the system  board ( with screwdriver )to see if that will prevent this shutdown event from occurring. Maybe the eprom has bad code lurking and a simple reset is not doing anything to fix it.

Thanks,

Rick

 

 

[BrokenDW]

Terry maybe this is what you are asking here it is:

https://www.amazon.com/gp/product/B07HNL7SJT

Rick

 

[Terry Carmen]

If the part you linked to is the one that was open, it's a common failure point and needs to be installed along with the wires and wire connectors in the kit, and not just plugged into replace the old one.

 

Edited December 15, 2021 by Terry Carmen

[BrokenDW]

Correct. And I did that say a month ago. So now I am just troubleshooting it, and found at room temp it is 0.3 ohms, and when the dishwasher shutdown I tested it again and it was 0.1 ohms. I did not test as say an open loop so to me other than the drop in ohms that part is good. And when placed back onto the control board and powered up the dry cycle ran with any issue. But having said that it always shuts down right before the dry cycle, and maybe it is not this fuse that is causing the problem. I could always buy another for $10 but I am wondering if something else is wrong.

Rick

[BrokenDW]

Just now, BrokenDW said:

Correct. And I did that say a month ago. So now I am just troubleshooting it, and found at room temp it is 0.3 ohms, and when the dishwasher shutdown I tested it again and it was 0.1 ohms. I did not test as say an open loop so to me other than the drop in ohms that part is good. And when placed back onto the control board and powered up the dry cycle ran with any issue. But having said that it always shuts down right before the dry cycle, and maybe it is not this fuse that is causing the problem. I could always buy another for $10 but I am wondering if something else is wrong.

Rick

dry cycle ran with any issue   <---- is really dry cycle ran withOUT any issue

[Terry Carmen]

6 minutes ago, BrokenDW said:

and found at room temp it is 0.3 ohms, and when the dishwasher shutdown I tested it again and it was 0.1 ohms. I

That's the resistance of the connection between the device and your test leads or probes. Replacing the thermal fuse again won't help.

[BrokenDW]

I do not understand what you mean. I fully removed the bimetal fuse from the dishwasher I had it in my hand, I then tested the bimetal fuse and it was 0.1 ohms. I was watching my multimeter and gradually the ohms started to move towards the 0.3 ohms after about 3 minutes. I then removed the multimeter from the totally isolated bimetal fuse and placed the fuse back onto the control board. I then put back all 6 torx screws and turned the power back on and from there it ran fine.

"That's the resistance of the connection between the device and your test leads or probes. Replacing the thermal fuse again won't help." When you say device here do you mean the multimeter is the device? Or the wires from the control board is the device?

Again the bimetal fuse registered 0.1 ohms away from the dishwasher( after fully removing it from the control board), one hour prior the bimetal fuse registered 0.3 ohms away from the dishwasher.

Maybe you are still saying replace the bimetal still after I explained in detail what I did?

Thanks,

Rick

 

[Terry Carmen]

0.2 ohms difference  is insignificant in relation to the problem you're having and is almost certainly caused by differing resistance in the way you connected the test leads to it. 

I'm not sure what's wrong with your dishwasher but can tell you that replacing the thermal fuse will not fix anything, regardless of whether you're getting 0.1 ohms or 0.3 ohms.

[BrokenDW]

OK Terry thanks! I was thinking the fuse was OK but not positive.

Let me say this and I am no expert on this subject.

I think the following are OK:

1. bimetal fuse

2. control board ( except maybe buggy software code running in eprom on control board )

3. heater vent

4. heating element

5. high limit thermostat on back of tub

 

I think what I am trying to say is all of the parts seem OK, but the dishwasher still shuts down right before the dry cycle. So something is clearly wrong. Running without heated dry it runs perfectly. 

So other than the power cord issue ( which I did replace ) can you think of anything else?

Thanks,

Rick

 

 

 

 

[BrokenDW]

I think I found the problem, and this is the 2nd or 3rd time this has happened.

A blown capacitor. This seems to me to be an ongoing problem with whirlpool control boards. The one that has blown is always the same exact one.

So the only question I have, does anyone here know the conditions to make this happen other than cheap parts from whirlpool?

Thanks,

Rick

 

 

 

[BrokenDW]

I also found this info on capacitors.

 

https://resources.altium.com/p/electrolytic-capacitor-lifespan

 

What I don't know if this article is relevant to the issue with this specific capacitor. 

[BrokenDW]

Hello,

I am posting again to correct a mistake I made above. The capacitor is most likely not blown. Which means I am back to square 1 with this, not having an explanation to the cause of the power shutoff just before the dry cycle.

 

I am enclosing a close up, and it seems to me the capacitor is just fine.

 

Thanks,

Rick

[BrokenDW]

I think I fixed it. So the problem was the dishwasher would shut off, right before the dry cycle. So I decided to redo the connections for the thermal fuse. I did not change anything here, I simply removed over 4 wires from that terminal block, loosened the 4 very small screws as much as I could without them falling out, placing it of the 4 wires back into that block and tightening them down. I then added a strip of electrical tape running N to S around the plastic block and then one running E to W. I closed everything back up and ran a Light Wash cycle ( which by default includes Heated Dry ). I was watching the front panel indicators about 1 and 1/2 hours into the wash time ( it usually shuts down right here ) and it bypassed the shutdown and went right to the dry cycle.

So the lesson for me is, "even if the wires look solidly connected" take all 4 apart and redo the connection.

I hope this, "working condition" sticks around for at least another 10 times. 

Thanks to all who had some input on this.

Rick