Discharge damper, two-position motor and interlock: motor-operated parallel blade damper that prevents warm air from escaping the building through the unit. The motor-damper end switch energizes the starter circuit when the damper is in the full-open position, and returns to a closed position during shutdown.   Discharge louvers with air diffuser: discharges air in four directions with vertical and horizontal blades, and is field-installed. The blades can be manually adjusted to set direction of airflow.   Filter section: removable, hinged access door, with a 2-inch washable, aluminum-mesh filter, or a 2-inch pleated filter. Also available with 1-inch, 1.5 lb density insulation.   Inlet screen: prevents material from entering unit. A 1-inch mesh screen fastens to unit's fresh-air intake.   Return-air filter, 80/20 units: 1-inch or 2-inch deep, aluminum mesh, or 2-inch deep, 30% efficient, pleated type; v-bank, filter section shipped loose for field mounting to the return-air connection.