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Inglis dryer will not heat, thermistor suspected.

NXTreme

Premium Member
Joined
Sep 16, 2014
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6
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Alberta, Canada
Model Number
YIED7200TW
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1-5 years
Hey all! I'm new to the forums, and I've come with some questions about a malfunctioning dryer (did I come to the right place? ;)). I did not post this in one of the manufacturer sub-forums as none of them were applicable to the dryer in question, an Inglis #YIED7200TW. A bit about myself so you know my level of "electronics education." I'm an almost completely self-taught electronics hobbyist; I like to tinker with microcontrollers, sensors, and fix any electronic/mechanical device I can such as cellphones, computers and now dryers! I am competent with both a soldering iron and a multi-meter, though I definitely don't have the experience that a professional repairman would! I've been a part of quite a few online forums focused on electronics of various sorts over time, so I have some idea of the etiquette expected, but please let me know if there is something I should be aware of in that regard!

As the thread title states, I'm trying to fix an Inglis dryer (electric heat) that is not heating, though the tumbler (or drum, which of the two is considered the "proper" term?) still rotates normally. The dryer is my aunt/uncle's, they originally called the "official" repairman but he stated that it was faulty main control board, which would be about $380 to replace, and he suggested buying a new dryer. This conclusion surprised me as it is a new-ish dryer (just under five years) that has been taken care of quite well. My uncle ran it with the exhaust duct disconnected with the same result, which I believe rules out a problem in the exhaust ducting. It's been used as is with no heat for at least a month, and my aunt has noticed the back of the unit getting warm at least twice, though the wet laundry stays cool. When I took it apart to test components I vacuumed it out thoroughly, though as it has been taken care of there was what I'd consider a minimal amount of lint in it. I checked all the vents and tubing for blockage and found none. This leads me to believe it's an electrical issue.

Searches of the forum here have revealed two relevant threads that have helped to a degree: [http://www.applianceblog.com/mainforums/threads/30841-inglis-whirlpool-dryer-yied7200tw-how-to-replace-heat-element], and [http://www.applianceblog.com/mainforums/threads/40738-Inglis-Dryer-No-heat]. The former of those links led me to two very helpful documents posted by 'jeff1' that I've been using to diagnose my dryer problems. Some parts numbers have not corresponded to those in the machine I'm working on, such as the main control board which is model #MDE27 on the machine but #MDE6700 in the technical information document jeff1 posted. Nonetheless, I think I've tracked the problem down to a faulty thermistor. I will post my tests below for the experts, the measurements were all taken at approximately 24 °C and with the wires back to the control board disconnected. I've taken the part naming from the technical information document.

  • (Exhaust) thermistor = ∞ Ω
  • (Exhaust) thermostat 1 = 0.0 Ω
  • (Heating element) thermostat 2 = 0.0 Ω
  • (Heating element) thermostat 3 = 0.1 Ω
  • Heating element coil = 9.6 Ω, also checked for shorts between metal shroud and the element itself and found none.
  • Door switch when close, COM and NO are connected, NC is floating.
  • Door switch when open, COM and NC are connected, NO is floating.
After reconnecting the sensors I measured the sensor wiring harness at the main control board (though disconnected from board).

  • Pink wire pin 4 to Orange wire pin 5 is stated to be "sensor bars" (humidity sensor?), I only measured it without wet clothes, it measured ∞ Ω.
  • Blue wire pin 2 to Red wire pin 6 is stated to be the "cycling thermostat", it measured ∞ Ω. However, from the wiring diagram in the technical information document I believe to actually be the thermistor, not a thermostat.

The only anomaly I see is that of the thermistor, measured both at the sensor and at the control board it seems to have failed "open." Another thing of note, the door switch terminology used in the technical information document is confusing, as well as being reversed in logic according to my measurements. I also got into the diagnostics with the help of the document, I'll explain that below. I ran the LED/switch check for the fun of it, everything checks out fine.

I accessed the diagnostic codes by holding 'Chime' and 'Temperature' for three seconds and then pressing 'Wrinkle Prevent' (I don't know about you, but diagnostics usually cause me wrinkles, they don't prevent them! :)). I then rotated the dial clockwise, getting the following.

Code:
( d) - (02) - (11) - (10) - (--)
I'm partly confused by the result, as the 11 code and the -- code do not appear in the diagnostic codes in the technical information document. The 02 code would line up with what I tested myself though, a faulty thermistor! The 10 code is also somewhat confusing to me, what could I gather from it?

As per the manual, I also pressed the 'Start/Pause' button to get the number of cycles ago that the individual codes occurred at. One additional thing I noticed is that the 'Control Lock' LED lit up when the 02 code was displayed, and only when that code was displayed. I'll add the cycle count below the codes here.

Code:
( d) - (02) - (11) - (10) - (--)
         0     22     25
Does the machine remember codes and cycle counts despite a loss of power? I've unplugged it several times while tinkering with it, and we've also had several power outages due to heavy snow fall and downed trees last week, can I still rely on the codes being accurate?

That is all I can dig out of my brain and notes for now, I hope it's a sufficient starting point! I did take some pictures along the way, if they might be useful you can find them here [https://plus.google.com/photos/114837171770523347098/albums/6059867786848213985]. I'm sorry if I did ramble on, it seems like transferring all my mental notes to paper makes them twice as long. Maybe I should start compressing them... :wall:!
 
Last edited:

Jake

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Ok, looks like you've done your homework, but this model is Canadian Only, and we have no tech data sheet or service manual to cover this with you.

So you'll just need to rely on the tech data sheet that comes with the dryer.

You can PM jeff1 to see if he can assist you further, has a appliance shop in Hamilton Ontario: http://www.applianceaid.com/jrappliance.html

He's an appliance tech. that helps out here, hes a really good guy, he's been with us since 2004, you can contact him to see if he can assist you in this thread.

Jake
 

NXTreme

Premium Member
Joined
Sep 16, 2014
Messages
6
Location
Alberta, Canada
Hi Jake, thanks for the swift response!

Unfortunately, I'm relying solely on the data sheet that I found here on the forums even though it doesn't quite match up, as the dryer contained no data sheet as far as I could see. However, I shall PM jeff1 and see what suggestions he has. Thanks!

-EDIT- I'm unable to find the PM "button," I'm not sure if it's me lacking privileges or what. I'll just hope jeff1 stumbles across this thread. :)
 
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Jake

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Ok click here: jeff1

Then on the left side menu click Send Private Message.

Jake
 

jeff1

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dryer will not heat
Anybody confirm 220-240 volts AC is coming to the dryer?

The dryer is my aunt/uncle's, they originally called the "official" repairman but he stated that it was faulty main control board
Has anybody checked the relays on the board?...simply bypass the heat one by joining the wires together as a test....

01012992.jpg Main electronic control board

jeff.
 

NXTreme

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Messages
6
Location
Alberta, Canada
Anybody confirm 220-240 volts AC is coming to the dryer?
Hi jeff1, thanks for the reply! I checked the outlet as per the top diagram here and can confirm that the outlet is providing approximately 250 volts AC. I do not trust myself enough to poke around on the board with my multimeter while the unit is plugged in, so I cannot confirm in this manner that the power is reaching the board. However, I believe the next bit of evidence I found proves it does.

Has anybody checked the relays on the board?...simply bypass the heat one by joining the wires together as a test....
I bypassed the relay as you suggested, and ran the dryer for a short while. It definitely heated that way, and since the control loop was broken by bypassing the board it became very toasty indeed! This leads me to believe that the 250 volts AC is reaching the board. Would this mean I have both a dead thermistor and relay, or am I jumping to conclusions? Thanks for your help and time, I appreciate it!

P.S. I went ahead and unplugged the dryer to prevent it from being run after I bypassed the relay, as I'm assuming running it in this manner for any period of time >5 minutes could be potentially disastrous.
 

jeff1

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I'm assuming running it in this manner for any period of time >5 minutes could be potentially disastrous.
Yes, we just do this for testing purposes.

Would this mean I have both a dead thermistor and relay, or am I jumping to conclusions? Thanks for your help and time, I appreciate it!
I would say so yes.

jeff.
 

NXTreme

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How practical would it be for me to replace the relay? I have quite a bit of experience in replacing things such as capacitors on motherboards and power supplies, as well as other components. I'd just dremel out the epoxy surrounding the part, de-solder the relay and drop a new one in. However, in my experience relays have been some of the most durable components, especially compared to solid state devices, and I'm curious as to what could cause a relay to fail. Also, could the failure of the thermistor be related? I guess what I most want to know is if I replace the relay and the thermistor, what are the chances of one or either failing again?

Thank you once again for your help!

-EDIT- I believe this is the relay on the board, a SPST 30A relay from Potter & Brumfield. http://www.digikey.ca/product-search/en?vendor=0&keywords=T9AS1D22-12
 
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jeff1

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How practical would it be for me to replace the relay?
If you can find something, go for it.....an appliance tech would not....main reason is liability....we touch the board and solder in a new relay and something happens and that board/relay burns the house down we are liable, if we buy the whole control and something happens the manufacture of the board is liable and not us....this would be a worse case scenario.

I guess what I most want to know is if I replace the relay and the thermistor, what are the chances of one or either failing again?
Most times, something new breaks rather than the same item(s).

jeff.
 

NXTreme

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Messages
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Location
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If you can find something, go for it.....an appliance tech would not....main reason is liability....we touch the board and solder in a new relay and something happens and that board/relay burns the house down we are liable, if we buy the whole control and something happens the manufacture of the board is liable and not us....this would be a worse case scenario.
Understandable, I wouldn't necessarily want to be liable for a burnt down house myself! Given that I can purchase the relay and have it shipped to me for under $15 CAN, I think I'll give it a try. Also, would you be able to recommend to me a place to purchase the thermistor? Online would be preferable, but if you happen to know of a few places in central Alberta that would carry the part that would be great too.

Most times, something new breaks rather than the same item(s).
The reason I ask is that I've encountered several items during my "fix-it career" that have failed multiple times at one specific component, which could usually be traced back to a bad power supply, leaking capacitors etc. My favourite example is an individual's cellphone who's touch screen I replace three times in as many months. The root cause was a couple rambunctious kids, but I've encountered electronics with a more, shall we say, "electronic" defect? If you don't think the failure of the thermistor and relay are connected (as far as we can tell without doing a thorough inspection) or that they will fail repeatedly (again, as far as we can tell) I shall try replacing them!

Thanks again for all the help! I will attempt to take some pictures of the process of replacing the relay when that happens, and post them here in case anyone else ever encounters a similar problem.
 

jeff1

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