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-   -   Whirlpool Thin Twin, dryer thermal cutoff failed twice (http://forum.appliancepartspros.com/dryer-repair/322116-whirlpool-thin-twin-dryer-thermal-cutoff-failed-twice.html)

NorseGod 10-12-2011 10:17 PM

Whirlpool Thin Twin, dryer thermal cutoff failed twice
 
Friends Whirlpool Thin Twin came with purchase of condo half a year ago. A month ago it stopped heating. I checked continuity and found the Thermal cut-off switch was open. Purchased Dryer thermal cut-off kit and replaced as per instructions. Heat has returned and dryer works as designed.

A month goes by and dryer has no heat again. Check parts from the following diagram: AppliancePartsPros.com LTE6234DQ2

Part number: AP3094244

Part number: AP3094244
Dryer thermal cut-off: open (again)
Part number: AP2973862

Part number: AP2973862
Dryer high-limit thermostat: closed
Part number: AP2946932

Part number: AP2946932
Cutoff - tml: closed
Part number: AP3131939

Part number: AP3131939
Dryer cycling thermostat: closed
Part number: AP3134638

Part number: AP3134638
Heating element: closed, reads ~12 ohms
Checked both leads of coil to frame, all open

Before I go and replace this same part again, what else should I check? What other steps are necessary to diagnose the original cause of this failure?

Checked vent hose: clear of debris

denman 10-13-2011 03:40 AM

Sounds like the coil is OK but I would double check it. Also take a look at the inside for any sign that it has touched the case when hot. This is unlikely as it usually welds itself to the case but it can happen.
Check the heating coil.
Unplug the unit and both wires to the coil.
Check it with a meter, should be around 10 to 12 ohms.
Then check from each side of the coil to the case/frame, both should be infinite ohms (open). If not the coil may have sagged or broken and is touching the case. This can cause it to run on high and the thermostats cannot regulate it so the thermal cut-off blows.

The hi-limit should have regulated the temperature so the fuse did not blow, that is why there is a new one with the thermal cut-off..
Note: That unless there is another problem in the unit the hi-limit should never have to open. It is just a safety device with the fuse being a backup safety device.

Just in case it is not a grounded element.
With all the below the high limit will also have to be replaced.
Check that the belt is OK.
Check the seals (drum etc) in the unit. The air is pulled over the heating coils, through the drum and pushed out the exhaust. So any large seal leak will pull in room air and the cycling thermostat on the blower will run the unit hot.
Check that the lint filter is not coated with fabric softener residue which greatly reduces air flow.
Check/clean your vent system.
Check/clean the blower wheel.

If all OK you may want to replace the cycling thermostat as it's contacts may not be opening (welded shut)

kayakcrzy 10-13-2011 05:11 AM

If the vent to the outside is good, it is very possible that the cycling thermostat is the issue, because, the temp could be getting to hot, and blowing the thermal cut-of. As a serviceman I have been replacing the cycling thermostat when I have a thermal cut-of go out, because I have gone back to that customers house, in a few days, only to change the cycling thermostat, and it do it. Tom ********************************************

NorseGod 10-23-2011 03:01 PM

denman: had a look at all your issues listed, looks to be ok.

Popped out the cycling thermostat and it appears to be working fine, checked by putting it in the oven to heat and it opened, then closed again when cooled. The one thing though, there are another set of wires on this thermostat, purple ones. On the wiring diagram this appear to be the thermostat heater, and it was open both room temp and hot. Could this be the original source of the failure?

To re-iterate, this unit has had a thermal fuse blow twice now. The hi-limit thermostat was replaced after the first failure. Could a failed thermostat heater within the cycling thermostat be the cause of this issue?

Thank you all for your replies!

denman 10-23-2011 04:10 PM

1 Attachment(s)
In case you do not have the same one see the attachment for the wiring diagram.

Could a failed thermostat heater within the cycling thermostat be the cause of this issue?
It should not. If you look at the cycle chart the heater is off in high heat selections.
It does need replacing and who knows maybe it is not opening at the correct temperature.
I cannot think of anything else because all other possible causes check out OK.

Opie1514 05-29-2012 06:22 PM

Same problem-Whirlpool Thin Twin, dryer thermal cutoff failed twice Reply to Thread
 
I am having the same problem a you had. I suspect the "thermostat heater" has gone bad, as my unit runs at high heat no matter the selector setting (fairly certain that selector is operating correctly, as the ohms increase as I turn dial to increase heat amount.

Can you tell me what you found to be the fix, as I hate to keep guessing and replacing expensive parts.

Thanks in advance.

Respects,

Mark


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