Kenmore dryer: why thermal cut off fuse?

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  #1  
Old 01-24-20, 10:33 PM
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Kenmore dryer: why thermal cut off fuse?

Why is it needed? Ive only repaired a few dryers, but this looks like extra part. This dryer has the std High-Limit Thermostat, Operating Thermostat, and Thermal Fuse. However, it also has this Thermal Cut-Off Fuse. This Thermal Cut-Off fuse is located in the heater housing where it feeds the drum and looks more like a thermostat. Its also the most expensive part.

See attached diagram.

#1 Thermal Cut-Off Fuse

#34 High-Limit Thermostat

#42 Operating Thermostat

#59 Thermal Fuse

kenmore 110.96281100

tks,
pa
 
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Old 01-25-20, 01:50 AM
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That is the first fuse that blows when the vent is clogged. Also ill blow if the heater is shorted. Have only seen this a few times. If you want the heater or thermostats to quit take it out and than the most expensive parts will go.
 
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Old 01-25-20, 01:57 AM
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Edit buttons don't work so a new post. Looking at picture are you talking about the thermostat at bottom of heater? If so I have never seen that one go out and I repaired dryers for many years, They come in a as a pair when you buy them from Whirlpool so I usually replaced it any way.
 
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Old 01-25-20, 03:38 AM
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They are all there for a reason.

The thermal cut-off and hi-limit protect the heater from overheating,
The heating coil can break and short to the case then that part of the coil becomes an uncontrollable hot area.
Also if the lint filter is clogged the heater can overheat due to low air flow through it.
Plus a few other things.
When this happens the heater runs on the hi-limit. Unfortunately most of the time people do not notice that the dryer is running hot so it keeps doing this. Also the hi-limit's contacts are not as good as the control thermostat's contacts so in time they fail. Often they fail by welding together then the thermal cut-off blows. That is why they are sold as a pair because the thermal cut-off should not blow unless the hi-limit has failed/shorted.

The most common cause of the thermal fuse to blow is a partial or full clog of the dryer vent.
It blows to protect against vent fires.

And the thermostat is there to control the temperature.
 
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Old 01-25-20, 05:32 AM
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I have old dryer that has bad thermal cut off. The other three r fine. If i bypassed it, would not the other listed fuse protect the clothes?
 
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Old 01-25-20, 06:05 AM
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It is not about protecting the clothes.
It is about keeping your house from burning down.
 
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Old 01-25-20, 06:11 AM
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Why other brands and other Kenmore whirlpool no hav? Why the other fuse?
 
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Old 01-25-20, 08:20 AM
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You find me make and model numbers of the units that do not use these and I will try to answer your question.

What other fuse?
Above I thought I covered the thermal fuse (on the blower) and the thermal cut-off (on the heater assembly)
 
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Old 01-25-20, 03:05 PM
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All dryers I have worked on have all the thermostats and thermal fuse.
 
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Old 01-25-20, 08:58 PM
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Ive watched several troubleshooting videos for this specific model troubleshooting for no heat. Each video tested the High-Limit Thermostat, Operating Thermostat, Thermal Fuse, heating element. One of the videos tested the timer. None tested or even mentioned the Thermal Cut-Off Fuse.
 
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Old 01-26-20, 03:04 AM
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Still need model numbers!!!!

For a no heat problem you check the thermal cut-off.
If the thermal fuse blows then the unit will not start.
 
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Old 01-26-20, 07:06 AM
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Those safeties are installed by the maker to give you the best chance of not burning your house down.
Relace it.
 
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Old 01-26-20, 11:17 AM
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Before I purchase new cut off, I decided to test the two thermostats:

one is marked L155-25F. it opens at 110F.

the other L250-80F. it opens at 180F.

Some sites say that number after the dash is +/- for opening temperature. Other sites say that is how much less the temp needs to be for closing. I dont know which sites are correct.
 
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Old 01-26-20, 02:40 PM
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Never checked one like that if open bad, closed good.
 
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Old 01-26-20, 03:04 PM
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As far as I know it is the latter (reset temperature difference)
 
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Old 01-26-20, 03:14 PM
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Looks like these two bad too then.
 
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Old 01-26-20, 03:24 PM
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No I would say that they are OK.
I do not know how you tested them to determine the trip temperature.
And I do not know how the manufacture came up with that spec.
As long as they open and close then I would not replace them.

There is onne scenario where the thermal cut-off can blow but the hi-limit is OK.
And that is when a heating coil breaks and part of it touches the case (grounded). It will then run uncontrolled and if it is near the cut-off it will blow,
 
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Old 01-27-20, 02:33 AM
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One other thought I had was did you use a meter to check that the contacts actually opened or did you just listen for the click?
I always use a meter!!!
 
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