A door operator operates a door that is rotatable about an axis of rotation between an open position and a closed position. The door operator comprises an output shaft, a closing assembly, and a motor. The output shaft is rotatable between a first position and a second position, and is coupled to the door such that rotation of the output shaft pivots the door about the axis of rotation and rotation of the door about the axis of rotation rotates the output shaft. The closing assembly is coupled to the output shaft to apply a torque to the output shaft, wherein the torque applied by the closing assembly rotates the output shaft such that the rotation of the output shaft by the closing assembly rotates the door toward the closed position. The motor is coupled to the output shaft via a clutch to selectively apply opening and/or closing torque to the output shaft.