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Author Topic: Help repairing old Whirlpool Dryer Model LE7680XSW1  (Read 604 times)

Offline reddgreen

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Help repairing old Whirlpool Dryer Model LE7680XSW1
« on: January 21, 2019, 10:38:41 AM »

Hi All
         have an old Whirlpool 220v electric dryer, model LE7680XSW1.   Prob mfg late 80's early 90's. 

Unit ran for over 20 years (old when we got it).  Stopped heating a few weeks ago.
Unplugged, measured sensors, etc, found that the thermal fuse mounted on the side of the heater box was open.
Ordered a kit that has a new thermal fuse and also high limit thermostat.
Unit ran one or two loads, fuse opened again.   

Got a replacement kit a little over a week ago.
This time checked again that the impeller wasn't broken, no missing fins, clean, no lint clogs.
Checked the vent pipe, clean.   Checked that the flap on the vent outside is not stuck.
Seems to be blowing plenty of air.

Put the second kit in.  this time the unit ran for about 5 or 6 loads.
Thermal fuse opened again. <big frown>

As far as I can tell,  I really don't think the heater box made it up to 350 degrees to open that fuse.
The wiring is all clean, no brown/discoloration indicating overheating.   But I don't know for sure, I wasn't running
the unit with the back off. 

I did open the door quite a few times, put my hand inside, air seemed reasonable temp.    I got the feeling that they are not making these thermal fuses very well. Don't know what to do next.

Any suggestions what to do next, greatly appreciated.

Thanks
Mike


Offline manden

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Re: Help repairing old Whirlpool Dryer Model LE7680XSW1
« Reply #1 on: January 21, 2019, 11:19:56 AM »
Did you check the heater with a meter to be sure it was not grounded?

Offline dab147315

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Re: Help repairing old Whirlpool Dryer Model LE7680XSW1
« Reply #2 on: January 21, 2019, 11:29:49 AM »
Tech Sheet and Parts List!

Offline reddgreen

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Re: Help repairing old Whirlpool Dryer Model LE7680XSW1
« Reply #3 on: January 21, 2019, 08:14:51 PM »
Thanks, yes, checked the coil with a meter, its 10.3 ohms,  about mid range as far as I can tell by some parts sites.   Also, I pulled the heater box out, and slid the coil out, nothing bent or broken, ceramic spacers are all there.  Doesnt look like cols were touching anything.

And thanks for the parts and repair info!!
« Last Edit: January 21, 2019, 08:20:16 PM by reddgreen »

Offline reddgreen

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Re: Help repairing old Whirlpool Dryer Model LE7680XSW1
« Reply #4 on: January 21, 2019, 08:17:50 PM »
Thought about it a lot, and I had 3 high limit sensors in there: original, replace 1 and 2. Wouldn't the high limit have to blow out to get the thermal fuse to die, if it was an overheat situation?

Offline manden

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Re: Help repairing old Whirlpool Dryer Model LE7680XSW1
« Reply #5 on: January 22, 2019, 04:35:23 AM »
Yes normally the hi-limit has to blow out (contacts welded together) for the thermal cutoff to blow.

It is best to use a meter when checking to see if the element is grounded with the element in place.

Offline manden

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Re: Help repairing old Whirlpool Dryer Model LE7680XSW1
« Reply #6 on: January 22, 2019, 05:18:41 AM »
Just had a thought.
Check the holes at the back of the drum to be sure they are not made smaller by fabric softener residue.
This can build up over the years and reduce the air flow over the heating element.


Another thing to be aware of is that the hi-limit thermostat will regulate the heat for a while but it's contacts are not as good as a heat regulating thermostat so after a while they fail (usually weld together) and the thermal cut-off then blows.

Offline Atech

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Re: Help repairing old Whirlpool Dryer Model LE7680XSW1
« Reply #7 on: January 23, 2019, 08:10:00 AM »
That's a good design, and we normally don't see repeat problem of thermal fuses opening. The high limit T-stat is in a good position, and will normally cycle before the limit opens.

Sometimes the original failure was do to heavy lint build up on the lint filter. If it's to thick it will peal off, and get lodged in the bottom of the filter housing. this totally blocks the air flow. You can run the dryer with the vent disconnected and you should feel very strong air flow at the rear of the dryer.

Another problem is, if the felt drum seals are bad, it will not pull the air through the heater, and cause it to get too hot. Are your drying times extended when it does work? We will usually run a load with the vent disconnected to isolate if the problem is in the dryer or the vent.

Good luck!

Dave

Offline reddgreen

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Re: Help repairing old Whirlpool Dryer Model LE7680XSW1
« Reply #8 on: January 27, 2019, 07:42:55 PM »
Thanks for all the help and suggestions everyone, this is awesome. 

Well, I went back and took the heater coil housing off, and carefully took the coil out.   Surprisingly good shape for its age.    The ceramics are not broken, the coil is not bent or broken.    I put the coil back in, tested for continuity between each contact and the case, and got no reading.    I put it all back together, measured again,  resistance across the coil is steady 10.3 ohms, and no continuity between the case and either of the heater contacts.

I did notice one thing though, maybe not an issue:   when I took the coil housing off, the connection to the back plate, there was a little space there on one side. Like the housing had been pulled back slightly.  I pushed it in where I thought it should go, bent the bracket on top, and screwed it back together. No space there now. Maybe that was contributing.

With the back off the unit I ran it for a while (fuse is bad so no heat) but get a lot of air flow, at least seemed ok.    Did not find any lint build up anyplace. Im religious about cleaning the lint trap (although my wife forgets sometimes, I have to remind her that it could catch on fire if it builds up).

Ahh, just re-read your post Manden about the cycling thermo.  OK maybe that failed closed (shorted).   
So, the first time I replaced just the thermal fuse, not the high limit + fuse.  That lasted like one load.  I got the replacement and replaced both.   (had to remind myself why I have an unused high limit thermo).    The second repair lasted 5 or 6 loads.

So, if the cycling thermostat went bad, the high limit lasted a while but eventually dies and takes out the thermal fuse.  Arrghh.  Wish I knew to test the cycling thermostat.

Can I test the cycling thermostat by putting my voltmeter on AC, putting clips onto 2 of the contacts (not sure which 2 as there are 4),  then turning the unit on?   If the unit runs for a little while,  30 seconds, or something like that, I should see a voltage when the cycling thermostat opens?     

How long should I let it run before I turn it off to be sure the cycling thermostat is not opening correctly.  Is like 30 or 45 seconds OK?    It must beat up those old coils pretty badly.


Thanks!!
Mike
(just back from laundromat :( )






Offline reddgreen

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Re: Help repairing old Whirlpool Dryer Model LE7680XSW1
« Reply #9 on: January 27, 2019, 09:51:23 PM »
Dave, regarding extended drying times, I don't remember, but my wife usually does the laundry (she doesn't like the way I mix stuff up).      But as far as I know, everything is original except the two sensors I put in.   

Is the felt like a kit I can replace?

Offline dufuss

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Re: Help repairing old Whirlpool Dryer Model LE7680XSW1
« Reply #10 on: February 07, 2019, 12:20:28 PM »
 I am inclined to suspect the felt as Atech suggested.

    https://www.repairclinic.com/PartDetail/Felt-Seal/279408/3028

             VIDEO                  https://www.youtube.com/watch?v=Ln0L6EtDU6M
« Last Edit: February 07, 2019, 12:23:00 PM by dufuss »