A ventilating air and airflow control in a ventilating, heating or air conditioning system is provided. A structure and method to provide air flow mixture via an air mixer structure or `baffle` located within a blend door are provided.The simplified HVAC unit provides a baffle/blend door assembly comprising an air mixer structure wherein the attachment means of baffle and barrel door is such that it provides for ease of assembly. The baffle/barrel door assembly provides for smaller packaging volume with the same functionality as larger HVAC units.