Troubleshooting a Kenmore dryer that keeps running is something that almost anyone can do with the use of a few simple hand tools and a digital multimeter. The cause of a Kenmore dryer that keeps running -- or any dryer that keeps running -- can usually be traced to a defective door switch or a malfunctioning timer control. Before performing any troubleshooting on any dryer, unplug the the unit from its wall receptacle.
The Door Switch
The door switch is a simple, normally open microswitch connected in series with the drive motor circuit. The purpose of the door switch is to disconnect the drive motor from its power source when the dryer door is opened, then reconnect the drive motor to its power source when the dryer door is closed. The dryer door switch takes a real beating every time the door is opened and closed. When a door switch fails, it usually fails where the internal contacts do not close or where they become stuck in the "Closed" position. In the former state, the dryer fails to tumble; in the latter state, the dryer continues to tumble even after the door is opened. To check the condition of a door switch, set your digital multimeter to its R X 1 scale or its “Continuity Test” position, if it has one. With the door open, a good switch will display an “O.L.” on the meter's LCD when the function switch is set to the R X 1 setting or emit no tone when set to the “Continuity Test” position. With the door closed, a good switch will display an “0.000” on the meter's LCD or cause a steady tone when the meter is set to “Continuity Test.” If the meter displays an “0.000” when the dryer's door is open, the switch is defective and needs to be replaced.
Timer Does Not Move to the "Off" Position
If the timer remains in whatever cycle you place it in when beginning the dryer operation without advancing steadily to its “Off” position, the dryer will continue to run as long as the door is closed. The timer is a motor-driven, multiple-contact switch that controls the drive-motor circuit and the circuits for the heating element. In the "Off" position, the internal contacts controlling the motor and heating elements open, disconnecting them from the power source. A separate set of internal contacts open, disconnecting the timer motor from the power source. A timer that fails to advance could have internal contacts that are not closing or a timer motor with an open winding. To check the contacts, set the timer to any position other than "Off" and take a continuity reading through them. To test the timer motor, disconnect one of its leads and take a continuity reading between them.
Timer Advances to "Off," Dryer Comtinues to Run
A Kenmore dryer may fail to stop running because one or more sets of the drive motor's timer-controlled switch contacts are stuck in the "Closed" position. To check these contacts, unplug the timer's wiring harness plug. Find the proper terminals -- using the contact drawing with the wiring diagram on the back of the dryer -- and take a continuity reading through them. With the dryer in the "Off" position, all of these contacts should be in the "Open" position and the meter should display an “O.L.” on its LCD.
Short in the Wiring Harness
A less common cause of a dryer that continues to run is a short in the wiring harness that bypasses the door switch or timer motor-control contacts. Short circuits can usually be detected with a visual inspection of the wiring. Look for bare wires touching or for signs of burned or scorched insulation.