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hamiltzp  
#1 Posted : Tuesday, November 26, 2013 2:47:37 PM(UTC)
hamiltzp

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Posts: 5

Hello,

I have a Maytag dishwasher, model MDB5100AWB, that has stopped drying the dishes. The "heating delay" function is also suspected not to be working because it is leaving a mild soap residue on some dishes.

During the middle of a dry cycle, I reached in and was able to touch the element with my hand, so I don't believe it is working. However, when I removed the element and set my analog multimeter at X10, I got a reading of about 2 ohms. My understanding from various online resources is that it should be OK based on this reading. If I'm doing it wrong, please let me know.

I wanted to test the leads going to the element from the dishwasher to see if the element is getting current, but I wasn't sure how to set my multimeter. I'm also not sure how to proceed overall, since the element itself appears to be OK, yet it is not working.

Any guidance anyone can offer would be appreciated.

Thanks,

Zack
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denman  
#2 Posted : Tuesday, November 26, 2013 4:22:46 PM(UTC)
denman

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Here are your parts, includes a wiring diagram.
Parts for Maytag MDB5100AWB Dishwasher - AppliancePartsPros.com

You will notice that there is a limit switch (item 16 in section 6) in the heater circuit.

Remove power from the unit and check it.
It should be 0 ohms.
It will be clamped onto the bottom of the tub (I think)
hamiltzp  
#3 Posted : Wednesday, November 27, 2013 6:25:02 PM(UTC)
hamiltzp

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Hi Denham,

I found it and removed it. It checked out at 0 ohms. What next?

Thanks,

Zack
denman  
#4 Posted : Thursday, November 28, 2013 3:32:25 AM(UTC)
denman

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I would measure from the White at the door switch to the Orange at the control board (see the wiring diagram). If this measures the 20 ohms of the heater then odds are that the control board is toast.

You could also check the thermistor resistance.
I do not have specs for this unit but usually they are around 10,000 ohms at room temperature. The resistance decreases as temperature increases.
This is a bit of a long shot as I do not think that the thermistor is used/monitored during the dry cycle but am not 100% sure of this.
hamiltzp  
#5 Posted : Thursday, November 28, 2013 9:07:51 PM(UTC)
hamiltzp

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Denman,

Hmmmm. I think I just learned how to read my multimeter correctly, so thanks for your patience. :)

I measured from the spade connector on the element where the white wire would go to the spade connector on the limiter where the orange wire would go and got 20 ohms, so that's consistent.

I think I found the thermistor under the tub. It had a brown and gray pair running to it, anyway. It reads at 40 at 1k, so that's 40,000 ohms, correct? That sounds a little out of spec.

I was also studying the wiring diagram, and I was also already looking at the circuit board with suspicion. If that's the problem, then I see a new dishwasher in our future.

Is there any way I can bypass the thermistor, even for just a couple of minutes, to see if that's my problem? My wife is becoming impatient and would like to go buy a dishwasher since they've got some good deals right now.

Thanks again for your help!

Zack
denman  
#6 Posted : Friday, November 29, 2013 4:57:46 AM(UTC)
denman

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Posts: 19,638

[COLOR="Blue"]It reads at 40 at 1k, so that's 40,000 ohms, correct?[/COLOR]
I would say yes.
Sounds like an analogue meter and I have not used one of these in the last 30 years or so I hope my memory is OK.

[COLOR="Blue"]That sounds a little out of spec.[/COLOR]
Yes it is if the Q&A for that part is correct.

[COLOR="Blue"]Is there any way I can bypass the thermistor, even for just a couple of minutes, to see if that's my problem?[/COLOR]
Yes but be very careful that you do not let it run very long as this is a safety/fire hazard.

Then start a cycle that heats the water.
Check the water temperature just after the water enters the unit.
Then check it after a minute or so.
The water will probably not heat up.

You could get a 10,000 ohm resistor and attach it on the board where the thermistor is attached.
Run the above test again.

If the temperature rises then the thermistor is toast.
hamiltzp  
#7 Posted : Sunday, December 1, 2013 3:46:40 PM(UTC)
hamiltzp

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Joined: 11/26/2013(UTC)
Posts: 5

Hi denman,

I just wanted to close out this thread.

I bypassed the thermistor during the dry cycle only, first for just a minute, then a couple, etc. I eventually left the bypass hooked up. It didn't make a difference, so I'm assuming your earlier statement was correct that the thermistor isn't used/monitored during the dry cycle.

I guess that leaves a $200 control board, and that's not going to happen. We're getting a new dishwasher. It's a shame. I was looking at the new ones and the elements seem to connect in the back now, whereas on my Maytag they connected in the front. I never had to pull it out once to do any of the troubleshooting we did, nor would I have had to in order to replace any of the parts we talked about. Oh well...

Thanks again,

Zack
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