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TL

Dishonerable dryer too hot. Vent not plugged.

35 posts in this topic

Disobediant wife shrinks clothes. This is good when it is her clothes, but not good when it is my clothes. On threat of violence, wife now cleans lint filter regularly. Clothes still get small. Not good.

Six months go by. Wife goes on vacation and I must wash my own clothes. Now I decide to fix dryer!

I am not a samurai, but I am an engineer. I design airplanes: I should not fear a dryer!

I check duct. It is short and has only one bend. No lint in duct. I take apart dryer and find temp selector. I check against schematic inside dryer: should be, High> 10k ohms, Med = 6200 ohms, Low = 0 ohms. But low is > 10k ohms, also. I buy new temp switch, test good. But dishonerable dryer still dishonerably hot.

I take out operating (cycling) thermostat, and test with hair dryer. It switches off and on. I check thermostat heater, and it is good. I take out timer switch, test against confusing schematic. Seems good as well.

But dryer still dishonerably hot, EVEN IN FLUFF MODE. This engineer can read jet airplane schematics, and house wiring schematics, but Whirlpool has defeated me. I humbly seek guidance from the masters.

-TL

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Need appliance parts? Call 877-803-7957 now!

Gas or electric?

Replace the operating thermostat, it may be working outside it's designed temp range.

If it's electric, make sure the element isn't grounded out inside it's case.

Nick

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Good idea!

I will check, but according to the schematic, one end of the heater is connected to ground through the motor switch. In other words, shorting to ground shouldn't do anything.

On the other hand, I'm not sure how much I trust the schematic that came with the dryer...

So far, I've been trouble-shooting by continuity, not voltage. I think I'm going to have to open this thing up with live 220v and poke around. If you hear sirens, my test probe shorted across two contacts.

-TL

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The heating element is inside of a metal canister, if the element coil is touching this canister or the bracket it is strung in, the element would be grounded and would never shut off, even in air fluff as long as the timer was turned on and the dryer plugged in.  You would be feeding 240 volts thru the whole dryer at all times, including the case as every safety in the dryer would be by-passed.....every thing in this dryer is 115 volts except for the heating element.  Something has your heat circuit grounded, suspect the element first...  Cute Doggie!!  :P

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Well, I've attached the alleged schematic I found inside the dryer. At first (thinking 110v) I thought that a shorted element couldn't generate any heat, because you would just connect the short to neutral.

But this is 220v, so connecting the short to neutral gets 110v whenever the timer is on! Ah! I see said the blind man, and he picked up his hammer and saw!

I will test for this ASAP. Danke!

:)And the dog pic is from a Basset rescue site. I used it because I live in Woodinville, WA, which has an annual Basset hound parade every April Fools day.

-TL

post-2210-129045085614_thumb.jpg

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Took a few days to get around to this, but it worked! :D

I took the heater apart and found one of the ceramic insulators had pivoted, allowing the coils to touch one of the supporting metals parts.  I twisted the insulator straight, bent the tabs around the insulator to prevent it from rotating back, and ta-dah!  Everything works!  THANK YOU ALL FOR THE HELP!

Not too thrilled with the design tho.  It seems to be poor design practice to have a circuit where a sagging heater coil can defeat all the safety devices preventing the heater coil from overheating.  As a child, I was taught to never leave the house with an appliance running, and this certainly reinforces that advice.  If we made jetliners like this, no one would fly.  Of course, dryers don't cost $35 million & up, either.  ;)

-TL

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I would strongly suggest you change this element. If it did this it will almost surely do it again. For safety's sake, DO IT.

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[user=437]exsearsguy[/user] wrote:

I would strongly suggest you change this element. If it did this it will almost surely do it again. For safety's sake, DO IT.

I did replace it.

And the dryer is again dishonerable!  ARRGH!

I had the heater sitting on the shelf for almost half a year before I got around to installing it.  After all, everything was working, right?

So I put the new heater in about a year ago and now the annoying wife* says the dryer has been overheating for months!  We have new little 6 month old samurai.  He keeps getter bigger - we don't need his clothes getting smaller!

Last month the washing machine drive coupler wore out, which was a quick fix.  But this dryer thing is making me look bad.  Wife actually wants me to call "real repairman" or buy new dryer.

Suggestions?

-TL

*Of course, wife might be annoying because yesterday morning a little old man backed broadside into her brand new Subaru  (3 weeks old and 750 miles on the odometer).  Crunch!  It's my fault because I was sitting behind the wheel when he hit the car.  And because I'm male.

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Oh, and when the dryer is set to "Low Delicate Medium Rare" the heater coil visibly cycles roughly every 55 seconds.  The temp (measured with a very reliable $1.99 oven thermometer), is ~150 deg F.

When the dryer is set to "High Heavy Flame Broil", I watched the heater until I got bored and started to drift off, nearly drooling into the 220V circuit.  It took a whole 85 seconds ( 1:25 ).  Oven thermometer reads ~175 deg F.

Wife says "Low Delicate" used to be sort of a luke warm wind, not a 150 deg F toaster.

-TL

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Can we get a model number please?

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LER7646EQ0 - I found this by dumb luck AccApp - he had penciled it in on the previous attached schematic...engineers!

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I would first check the resistance of the thermostat heater, the two violet wires go into it. Wouldn't hurt to check the temp selector switch. Oh, who am I kidding?! I would just replace the operating thermostat.

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[user=9503]AccApp[/user] wrote:

I would first check the resistance of the thermostat heater, the two violet wires go into it. Wouldn't hurt to check the temp selector switch. Oh, who am I kidding?! I would just replace the operating thermostat.

Thermostat heater = 6.9 k ohm.  Just checked that.  It's within the permitted range. 

I'll buy or order one tomorrow. 

And KurtiusInterupptis:  For why the "engineers!" comment?  You wouldn't have any applicances to fix if there weren't any engineers to design them wrong.

-TL

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Did you check the temp selector switch?

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The temp selector is brand new! 

After all, I replaced it only 2 years ago.  :)

-TL

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you say you cleaned the vent recently, did the cleaning include checking to make sure the flap on the vent hood on the exterior of your home is opening fully, or a plugged screen covering the vent on the outside of the house

 

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Whoa there parder... didn't mean to offend yo delicate professional sensibility's - any professional technician who has had the pleasure of servicing in the home of a PE understood and appreciated the humor conveyed in that post. In other words - It's a joke ,so you can retract the claws- please continue to churn out new appliances so I may continue be gainfully employed:?

 

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I know you said you cleaned the vent and all but this sounds like an air flow problem to me, especially with all the measurements on the operating thermostats and timing the elements cycling.  You also said something about a young Samurai.  Young Samurais have been known to get up in the middle of the night and place their socks into appliances to distract their parents.  Most of them go directly to the washer and put socks in the pump, however you seem to have a young samurai with imagination, one who undoubtedly seeks fulfillment on the higher plane of contorted parents. 

Since you have been into the back of the dryer (often) you should be familiar with the brownish-black tunnel that runs from the top (lint trap) down to the blower.  You may as well remove this and inspect it for missing socks or other possible blockage.  There are about 4 screws attaching it to the blower housing and 2 at the top where the lint trap lid is.  Look down inside the blower housing as well, sometimes there is an abundance of lint that can build up there, especially if the lint screen has pealed lint off before it came out for cleaning.

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Oh, and when the dryer is set to "Low Delicate Medium Rare" the heater coil visibly cycles roughly every 55 seconds.  The temp (measured with a very reliable $1.99 oven thermometer), is ~150 deg F.

When the dryer is set to "High Heavy Flame Broil", I watched the heater until I got bored and started to drift off, nearly drooling into the 220V circuit.  It took a whole 85 seconds ( 1:25 ).  Oven thermometer reads ~175 deg F.

We are looking for average temps, not high points.  The difference on many dryers between Regular and Low can be a difference of as low as 10-12 degrees and be considered normal on a properly vented unit.  If you are averaging 155-160 ish on regular, and a lower temp then that on Medium and a lower temp then that on low, your are probably within specs.  Delicate is not just a breath of warm air.  It usually will have an average of 135-145 depending on make and model.  Some units will offer a ultra care selection which might go as low as 120-125 degree average, but this is achieved via a different t-stat, or a thermistor and board combo.  I have never seen temps much different from what I have listed on units using a t-stat and bias heater like your system.  Problem with the thermometer you purchased is it will probably not react quick enough to accurately show you the temp swing.   

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[user=4044]Trying to help[/user] wrote:

Oh, and when the dryer is set to "Low Delicate" ...the temp ... is ~150 deg F.

When the dryer is set to "High Heavy Flame Broil"...  Oven thermometer reads ~175 deg F.

(1) We are looking for average temps, not high points. 

...

(2) If you are averaging 155-160 ish on regular, and a lower temp then that on Medium and a lower temp then that on low, your are probably within specs.

(1) Over thermometers are not known for fast response.  I consider the temps shown to be averages.

(2)  Ah, but I am getting 150-ish on Low, not regular.

Voltage to the bias heater is 0 on high, ~67 Vac on Med, and ~115 on High.  So the temp selector is good.

But check this out:  this thermostat is stamped "150F - 25".  Which implies to me that it is 150 degs with the bias heater OFF, and roughly 25 deg F cooler with the bias heater ON. 

I'm getting 150 deg F with the bias heater ON, and roughly 175 deg F with it off.

So I did some pondering.  Since everything generally flows from a single root failure, I figure the order of events was: 

  1. 3 years ago the temp selector failed so that the heater always ran on high.
  2. After a year of that, the heater wires sagged a little and shorted to the case and now it was on high even on fluff mode.
  3. So I replaced the temp selector (verified bad) and fixed the heater (verified bad) which I eventually relaced on the advice of "Sublime Master" [user=437]exsearsguy[/user].
  4. So now I'm wondering if maybe around the same time, the bimetallic thingy in the thermostat got permanently bent from the overheating, and now it reads wrong.

Counterindications to this theory:  The dryer worked for about a year after I replaced the temp selector and bent the heater wires back into the right shape.  But even master  [user=9503]AccApp[/user] suggested changing the cycling thermostat, so I did.

No change.  Verra mysterious. 

-TL

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And KurtiusInterupptis: For why the "engineers!" comment? You wouldn't have any applicances to fix if there weren't any engineers to design them wrong.
KurtiusInterupptus wrote: Whoa there parder... didn't mean to offend yo delicate professional sensibility's - any professional technician who has had the pleasure of servicing in the home of a PE understood and appreciated the humor conveyed in that post. In other words - It's a joke ,so you can retract the claws- please continue to churn out new appliances so I may continue be gainfully employed:?

Sorry.  No claws out.  That was just the sorry excuse for humor that I make do with around here.  Tell you what: If I ever do go into applicance design, I promise I will make it up to you by designing an especially bad appliance just for you.  :D

And regarding my current job, I assure you I had nothing whatsoever to do with the part that broke and delayed your last flight to Vegas.  Really, that was some other guy, not me.  Stop looking at me like that. :?

-TL

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So the new thermostat didn't help, which I think is the first part I've replaced that didn't need fixing.  New idea.

5.  Maybe the impeller got slightly damaged during the overheat, so there's OK airflow, but not good airflow.

So I took apart the hot air exit duct + lint filter holder thingy.  Double handfull of crap in the bottom, which I dutifully removed.  The impeller looks great.

But the foam seal between the drum and the exit duct looks awful.  Shrivelled and distorted and unhappy.  I think, "Aha!  The Samurai will gasp in wonder!  I have a new problem that will amaze everyone."  New idea:

6.  The foam was damaged and shrivelled up when the previous failures caused an overheat.  Air is being drawn into the exit duct at through the leaky foam seal, cooling off the dryer air and thereby biasing the thermostat by ~25 deg F.

So I tested the air temperature in the exit duct by the thermostat.  On the "Low" setting it was ~135 deg F.  (And I verified that the thermal lag on the oven thermometer is huge - it took almost 5 minutes to return to room temperature.)  So the thermostat is working correctly!  Sounds like exactly what you would get with a serious air leak.  But how to seal it?

I dug around in my spare parts bin and found some high temperature HVAC duct foil tape.  Good to 200 deg F, and 100% airtight. 

I went back into Dante's laundry room (so skinny there's only 6" between the dryer door and the opposite wall) and sealed up 90% of the circumference.  Unfortunately, my hands are too big to tape up the very top, but I tried.  Only drawback: it will be a major female dog to get that duct off the drum if I ever have to take it apart again.

Result?

No change.

Arrgh.

-TL

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[user=2210]TL[/user] wrote:

 Tell you what: If I ever do go into applicance design, I promise I will make it up to you by designing an especially bad appliance just for you.  :D

I hear GE is hiring. It seems they did that already.

So, did you check the temp selector switch?

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Where are we taking these temps from?  The temps I quoted should be vent discharge temps from the rear of the unit.  Most manufacturers recommend testing temps here in the service manuals.  You can poke a hole in the vent to check it hooked up, and then remove the vent to see the differences.  Is this where you checked them from to give the earlier temp readings? 

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One thing to consider would be to change the specs of the design of the dryer and install a lower temperature cycling thermostat in place of the one it is designed for if this dryer from hell does not behave???  Like one rated for 140 degrees or so....just a thought here....

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