Kenmore Dryer overheating

[bugs]

Sears Kenmore Heavy Duty electric dryer
serial no. F30703582
model no. 110.7218622
30+ yrs. old

Problem began with dryer shutting itself off mid-cycle. dryer was extremely hot to the touch. i pushed the start button and could hear a faint whirring noise but drum did not move. i opened door and didn't know what to do. after an hour or more, i decided to try it again. it worked. every time after that, when i dried several loads in a row, it would shut off during 2nd or 3rd load, way too hot again. after cooling down, ran fine. i searched for answers and figured it might be a lint buildup problem so we did a thorough clean out and actually found very little. we did notice that the drum seal(back) was in terrible shape so we ordered one but never got around to replacing it. i began washing the lint screen with soap and water on a regular basis. anyway, after putting it back together, dryer seemed fine. it stopped shutting itself off. at times it did seem to get overly hot but it never shut down. several months go by. then recently the dryer started really overheating. clothes were so hot i couldn't remove them from dryer. top and back of dryer were fire hot. and the clothes smelled scorched. we again opened up the dryer, cleaned out the back and the dryer duct. replaced the seal on the drum and found lots of lint in the front section of dryer. cleaned everything we could find and put it back together. it continues to get super hot so in order to use it now i have to use the air cycle alternately with the less dry cycle. i have to babysit every load to feel for the top of dryer to start getting hot. when it does i either stop it and let it cool down or use the air cycle for awhile. yesterday, something was all over my clothes when i removed them. it was brownish black and when cooled hard and stiff and unremovable, odorless, like something had melted on them. these were whites and delicates and nothing would have been in that load to cause this.
any help at all would be greatly appreciated. ideas anyone ?

[Dan O.]

Fire hazard!!

clothes were so hot i couldn't remove them from dryer. top and back of dryer were fire hot.

An overheating dryer is a very real fire hazard! I strongly suggest you discontinue use until it can be serviced and repaired.


Poor air flow through the dryer is the most common cause of overheating of the cabinet. Without proper air flow the heat can not circulate throughout the dryer and the dryer thermostat can not control the air temperature because it can't sense it.

cleaned out the back and the dryer duct.

You cleaned the dryer venting all the way from the dryer to the outdoors? Plugged or poor venting (see the following link) is the most common cause of poor air flow through the dryer, leading to overheating.

LINK > How long can my dryer vent be?

Problem began with dryer shutting itself off mid-cycle. dryer was extremely hot to the touch. i pushed the start button and could hear a faint whirring noise but drum did not move.

The whole dryer might have shut down on the safety thermostat if overheated sufficiently. That could have been caused by a malfunctioning cycling (ie. temperature control) thermostat or poor air flow.

LINK > Kenmore 110.7218622 Cycling Thermostat

we did notice that the drum seal (back) was in terrible shape so we ordered one but never got around to replacing it.

That will also contribute to poor air flow through the dryer. It should of course be installed if it is needed.

yesterday, something was all over my clothes when i removed them. it was brownish black and when cooled hard and stiff and unremovable, odorless, like something had melted on them.

I don't know what that would be if it isn't some fabric that melted because of the heat. There might be a slim chance the front drum bearing ring (see the following link) might have deteriorated with the heat?

LINK > Kenmore 110.7218622 Front Drum Bearing Ring

JMO

Dan O.
Appliance411.com
The Appliance Information Site
=D~~~~~~

[HayZee518]

that blackish substance could have been a plastic belt from the clothes. have you checked the "reaving" [lost for words] of the heating element. it should be on porcelain standoffs from the metal shell. if the heating element is too close to the metal it will give you hot spots, but like Dan said poor air flow is a contributing factor. maybe, just maybe, your air flow fan is disintegrating and is getting sucked into the drum and melting. there are safety overloads at different places on the dryer. but because the dryer is 30+ years old they didn't install enough of them. normal places are the air duct, element plate, motor housing top of the dryer cabinet. they are a part of the master wiring diagram to shut off the heat and motor.

[On-TimeAppliance]

It could be a cleaning issue in your dryer vent hose or the vent in your wall. If you are sure this is clean, replace your dryer thermostats. Your cycling thermostat could be sticking closed.

[LazyPup]

I would begin by disconnecting the vent line from the back of the dryer then run a load. If the temp is high with the vent duct removed you know the problem is in the appliance. If the temp is correct with the vent line removed odds are there is an obstruction in the vent line.

[DuneMe]

Is there something you could run in your vent to see if it is clogged (a clogged vent is what I did think of first as well as these Smart Guys.)

[bugs]

we did replace the drum seal next time we opened it up.
we cleaned out the entire dryer of lint, and the vent ducting to the wall. our's does not vent directly outside, but rather thru a wall, under the floor of the house. i assume it goes under the house. could that be an issue?
is the front drum bearing ring located on the inside frame of the front of machine, where the drum fits up against it?
if the safety thermostat shuts down will it later allow the dryer to re-start?
does anyone know if my machine has both the safety and cycling thermostats? would both need to be replaced?
again, your help is so appreciated.

[bugs]

we have removed our vent from dryer and can look clean thru it. there was a little lint which we cleaned out.
so, if the vent issue is eliminated, what should we consider next? thermostats? element?

[Dan O.]

if the vent issue is eliminated, what should we consider next? thermostats? element?

A problem with the element will not cause overheating. Its failure could cause heating while not in use or no or partial heating only.

The thermostat failing to cycle properly might be the next most likely possibility for overheating. Whether that is due to a failure of the thermostat itself or still an air flow problem inside the dryer, I can't say. The blower fan could separate from the motor and cause air flow problems too although rare. There could be other possibilities as well.

JMO


Dan O.
Appliance411.com
The Appliance Information Site
=D~~~~~~

.

[HayZee518]

ok, so we eliminated the lint as the cause of the overheat. next look to the blower. move the dryer away from the wall put some clothes inside and start it. look with a flashlight at the internals that you can see from the back. look inside the top panel for a schematic or line diagram. this will tell you what components are connected to the heat and motor. everything on the right of the diagram beyond the motor and/or relays is the L2 line or one side of the 240 line. Everything on the left ladder is the hot line or the L1 hot side that feeds all the permissives [ thermal cutouts, switches, relay contacts, timer contacts etc] Everything in the middle parts are the interconnective wiring between the devices.
you did say that the vent line is a long one, going under the house to an external damper. This could present a back pressure to the blower, so the heat builds up in the first third of the duct.

[bugs]

how many thermostats will there be on my machine? both the safety and the cycling thermostats? and where might those be located? will i be able to tell they are no good by looking at them?

[HayZee518]

visually, no! you need a multimeter that measures ohms to see if the contacts are electricity wise continuous. the meter applies a dc voltage across the contacts and measures the ohmic resistance. it is your job to determine if this resistance is passible or presents a problem. I'm sorry to say that this doesn't come over night. It's years of experience that gives you the insight as to whether a circuit is good or bad.

[Dan O.]

how many thermostats will there be on my machine? both the safety and the cycling thermostats?

There are two thermostats, the cycling thermostat (responsible for maintaining the operating temperature) and a safety (aka 'high limit') thermostat for shutting down the heater in case of a runaway heat condition.

and where might those be located?

The cycling thermostat on your model might be on the blower fan housing.

will i be able to tell they are no good by looking at them?

No and it will be difficult to varify if they are defective at all for your symptoms.

A thermostat's contacts are closed until it senses the temperature it is designed to operate at and then those contacts open up to shut off power to the heater (see the following link). Those contacts would have to be shorted (never open up) to cause your symptom. That will be difficult to actually confirm.

LINK > Dryer Thermostats and Safeties

JFYI


Dan O.
Appliance411.com
The Appliance Information Site
=D~~~~~~

.

[HayZee518]

a thermostat, like a honeywell used in an oil burner circuit consists of a flat coil that expands or contracts on temperature rise and fall. this is connected mechanically to a mercury switch or a set of silver contacts. a thermostat in a dryer is a bi-metallic element. basically it is two metals that expand or contract at different rates causing one or the other to bend in one direction. when you adjust the thermostat you press a nylon pawl against the bi-metal so it contracts earlier or later when it is sensing heat. on the end is a contact that touches another contact to complete the electrical circuit. these can electrically weld themselves shut or closed. a thermostat can also be circularly shaped in the klixon overload design. in the center is a contact that touches another contact to complete its circuit. the disk bends in the middle to open or close the circuit.

[bugs]

remember i said something had melted onto my clothes? it happened a second time. then, i discovered what it was. the baffle inside the drum. (mine's plastic) i noticed it looked a bit warped so i felt all around on it, and at the back it is cracked and small pieces of it were missing. as i touched it, a piece broke off, and it is the exact color. have you ever heard of that happening before?
i've got 2 thermostats ordered now and i won't use my dryer again until they are replaced. hopefully that will fix my problem. thanks to all of you and this site for your assistance.