Kenmore 400 Dryer turns on normally on any setting but is not heating and does not shut off at end of cycle. Continues to advance through all settings. Have to open the door to stop.
If drive motor continues to run as timer advances through OFF position, then the timer is bad. This may also account for the no heat problem. Unplug dryer, set timer to timed dry cycle mid position and check continuity between timer R and OR terminals. Should be near 0 (zero) ohms. If open, you need to check the thermal cutoff, operating thermostat and hi limit thermostat to determine which is open.
Whirlpool 8299779 Timer - AppliancePartsPros.com
Eric