If it glows continuously, it's a bad flame sensor, Part #
338906. If it glows off and on, it's bad gas valve coils, Part #
279137. A dryer will not turn itself off in the automatic cycle if there's no heat.
Part #
338906 Flame Sensor,
AP2910747

Part #
279137 Coil Kit for Dryer Gas Valve (3 Coils),
AP3094108
