A damper actuator for a ventilation damper serves as both a control device for the ventilation damper and a fire and smoke rated device for the ventilation damper. The damper actuator includes a modulating motor controller, a two-point motor controller, and a thermal switch or switch like device that is operative to switch control of the motor from the modulating motor controller used during normal operation, to the two-point motor controller during a fire and smoke condition. The damper actuator provides an automatic and permanent disabling (by-passing) of the modulating motor controller functions the first time a pre-determined temperature level (switch point) is reached via the thermal switch or switch like device. Once the modulating motor controller is disabled, the actuator no longer supports the advanced motor control functions (i.e. the modulating control). Thereafter, the thermal switch or switch like device enables a two-point motor controller that is operative to put the damper into either a fully open or a fully closed position.