WOW what a great site!!
35 and this is only my second home repair on my own!

Ok I have a Whirlpool dryer I have taken it apart and cleaned it up I also believe I have narrowed the problem down. The dryer was turning off after about 15 minutes, once it cooled down it would start again. The motor runs fine and when I have the dryer set to fluff I have no issues.

I printed out the back schematic and have determined through reading here and on other sites that it is either:

Thermal Cut-Off
Thermal Fuse
Thermistor
High Limit Thermostat

All look easy enough to change out but I don't want to take them all off to take to my local appliance parts distributor. Can anybody help me with this as far as what each part might be called technically AND what part makes sense as my problem.

Thanks,
Equalizer

(I have looked through all the posts here to see if perhaps my question has been asked and I did not see it. If it has please kindly point me in the correct direction.)

The high limit thermostat is probably causing the shutdown. However it may be working fine due to another problem. Is the fan drawing plenty of aire over the heat coils? Is there any obstructions causing the air not to flow properly?

Or is the aire flow ducting drawing air from a laek not allowing the air to be drawn through the heating elements?

I would be checking the air flow before replacing the high limit stat,because the stat may be doing it's job.

The dryer is about 5 years old, the duct for the exhaustis about a foot long leading straight to an outside vent. I have checked and completely cleaned it out, it was not bad at all.

The air flow / circulation seems fantastic to me.

What you need to do is check each component for power or conductivity when the dryer stops. It can be done with a multimeter, but is easier with a voltage sensor. Hardware and home centers have them for about $15. Hold them near a hot wire, and the plastic tip glows red.

Quote:

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Originally Posted by labman

What you need to do is check each component for power or conductivity when the dryer stops. It can be done with a multimeter, but is easier with a voltage sensor. Hardware and home centers have them for about $15. Hold them near a hot wire, and the plastic tip glows red.

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I can do that, but and I don't mean to be over simplistic or seem to know the answer to my own question but knowing this:

Dryer runs fine without heat
Nothing is clogged
Flow of air seems very good
Dryer "senses" when it is to hot and shuts itself down but then will restart after it has cooled

Then I can rule out or at least say for now that it is not the:
Motor
Blower
Heating Element
Fuses are OK
Whatever it is that senses it's to hot
Other wiring and such

Leaving me to believe that whatever it is that controls the temperature is the culprit.

So my question becomes - does that make sense?
And What part would that be? I would normaly guess at thermostat but nothing is called that...

Unfortunately with my limited knowledge there are 4 things that have the "word" Thermal... I just don't know what is what:
High Limit Thermostat
Thermisto
Thermal Fuse
Thermal Cut-off

Thanks again

As long as the air flow is good, then seems the high limit thermostat is defective.

The heating elements should be installed in a sheetmetal tube. Mounted directly on this tube is the high limit stat, with two wires connected to it.

Find an appliance parts store, give them your dryer model number, and they should be able to identify the stat and give you new one. Might be good to bring along the heating element assembly, so they can match exactly.

Treat the elements with care. They can be somewhat brittle.Check them carefully and thoroughly for any breaks, replace these if necessary.

Don't worry about which wire goes where on the stat, it is only a switch, so it does not matter.

Hmmm, I reread your problem, and I may have misunderstood.Does the entire dryer shutdown? Meaning the motor stops? Then this is not the high limit thermostat causing the problem. If so it is the thermal cutout on the motor. This stat may be defective. It monitors the heating of the motor to protect it from over heating. Not sure exactly where this stat is, usually built onto or directly in the motor.

Look at the digram for the motor and see if this stat is identified, and determine if this is something you can replace alone, or does the motor need to be replaced.

Maybe I need to have made my last answer more detailed. The dryer quits because one of the components meant to prevent overheating opens the circuit. Some of them will close once they cool off. It is possible the thermostat is sticking closed and overheating the dryer. I am not sure how you would check that. Study the schematic. Does the thermal overload shut off all the power, or just the heating element? If it is just the heating element, the dryer should start back up at once if you turn it to air only. If not, likely it is the over load in the motor itself. Check the motor. If you have power to it, and it does not run, it is the motor over load. Another check would be if the motor has continuity, with the power off you should get a low reading between the terminals of the motor with an ohm meter.

The overloads will located on the air duct. Usually they are about 3/4'' around and 1/2'' high with 2 wires going to them. Again, with the power off, you should get a low reading between the terminals with an ohm meter.

Nice thing about a voltage sensor is that you can just follow a circuit with the power on, touching it before and after each component, and find the one with power before it, but not after.

Thermisters are harder to check. They have a small voltage that varies with the temperature, going back to a control that operates a relay. Check the easy stuff first.

Update:

Getting frustrated. I called the local appliance parts stores and described the problem to them like this.

Dryer shuts off after 15 min. It will restart on it's own once cooled down (approx 10 min)
All lint has been cleaned out.
All rollers and drum move smoothly.
Plenty of aiir circulation.

2 different places made me feel like I was a liar when I said the dryer restarts on it's own.

So I decided to verify - put in some dry stuff (I will try normal wet next time) run the dryer... it ran it's full cycle!! Ugh!! No problem.

I'm going to put the back on and run a normal load and see what happens.

For those that may be following this thread.

I have now run 3 normal loads through the dryer. We are keeping a very close eye on it though. It seems to be fine.

What I did exactly.

Took dryer completely apart
Cleaned everything
Oiled rotating parts including motor
Cleaned out vent opening and vent hose (not much of anything)
Ran a load on fluff
Ran a load with a handful of already dry towels
Ran a medium size load of normal wet laundry

Put everything back together and have run 3 loads all a little smaller than our usual and all seems well.

What I am going to do:
Keeping running reasonable size loads
Keep an eye on dryer

Start saving for a new one.

Thanks all of you for your help and I hope this in some way helps someone else out!!

Good Luck!!
EQ

This is beginning to smell like a bad connection. They can come and go every time you look at it cross eyed. Likely it would be a simple repair once you found it. If you buy a new one, I assume it won't be the place that suggested you are a liar. Not knowing what he was talking about plus insulting a customer?

Were you running the dryer empty to notice the problem?

If so it will get very hot very quick, causing it to go off on safety.

Either that or you fixed the problem while taking it apart and did not realize that you fixed something. I do agree with the loose connection possiblty. This is something you may have taken apart and corrected when you reassembled the unit.

And as far as the appliance parts store not believeing the unit will start up on it's own after shutting down due a safety device is defintiely a place to stay away from in the future. And pass their name onto anyone you know to not to do business there. May be worth a call to the owner/manager to let him/her know the help is not very helpful.

No I won't do business with those places, lol.

The problem initialy occurred when wife was running normal (ok, normal to her) size load.

I believe somewhere in my adventures of taking it apart a few times and cleaning it etc. that I inadvertently fixed the issue.

If anything else comes up I will keep you guys informed.


Thanks again!!