I have a Kenmore dryer (110.66814694) that shuts off part way through a drying cycle and it appears that it is from overheating. When it shuts off, the top of the dryer is warmer than normal to the touch and after it sits for a while you can start it again.
So far I have ruled out restricted air flow. The dryer vents outside near a door that is used frequently so I am familiar with what the normal airflow is and it seems to be normal. I have also checked for blockages and found none.
The motor starts and turns the drum normally. I have confirmed that by depressing the door safety switch manually with the door open and starting the dryer and it does turn normally. In addition, even with a full load if you select air dry with no heat it runs to completion and sounds normal.
That seems to me to indicate that it is thermostat problem. There are three thermostatic devices in this unit. There is a thermo cut-off (3399848), a thermostat 250F (3399693), and a thermostat internal bias (3387134). I believe that latter one is the problem and that it has failed closed. My reasoning is that if it was the thermo cut-off that turned the dryer off, it would not reset when it cooled. That leaves the other two and since it shuts off a higher than normal temperature it would seem the higher 250 degree thermostat is shutting the whole dryer off because the lower temperature internal bias thermostat did not turn off the heat.
Unfortunately there was no circuit schematic included with the dryer paperwork nor can I find one on-line so I have no idea if that is even the way the 250 degree thermostat works. Perhaps it only turns off the heater instead of the complete dryer which shoots my theory all to pieces.
I have not checked the continuity of the thermostats because since it is over heating, it would appear to indicate that they are all closed at room temperature, as I suspect they should be. I suppose I could take the internal bias thermostat off the dryer, attach a VOM to it with clip leads, stick in a baggy, and then put it into boiling water and see if it opens.
My thoughts at the moment however are that if someone here could advise me how the 250 degree thermostat works in the circuit, and if my reasoning is sound (big if), it would be reasonable to order the thermostat and have it on hand so I only had to pull the dryer out once.
Get Help from Bob Vila
- Give-Aways & Offers
- Monthly Must Do's
- DIY Project Ideas
- Step-by-Step Guides
- Inspirational Photo Galleries