A support for a motor, particularly for a motor vehicle heating, ventilation andor air-conditioning unit blower, includes a more or less cylindrical hollow sleeve intended to accept the motor, and a fixing housing intended to accept the hollow sleeve. More specifically, a combustion system is provided having a first combustion chamber and a premixer positioned proximate an outlet end of a combustion liner for mixing a second fuelair mixture with hot combustion gases and burning the subsequent mixture to achieve reduced emissions levels. The actuation mechanism is configured to move the ramp portion between the closed position and the open position.