An auxiliary power unit (APU) includes a controller that controls the position of an APU inlet door, and thus ram air flow to the APU, to ensure optimal starting conditions are attained and maintained in the APU during APU startup operations. The controller receives a signal representative of an APU operational parameter and, in response, to supplies APU inlet door position commands. An APU inlet door actuator is coupled to the APU inlet door and, in response to the APU inlet door position commands, moves the APU inlet door to the commanded position.