Description Spring return motors for two-position back draft, outdoor air changeover, zone, or minimum position damper control. Features Operate outdoor air dampers for combustion or makeup air in residential and light commercial applications. Operate changeover dampers for heating and cooling systems. Operate minimum position dampers for ventilation and similar applications. Include internal SPDT switch for controlling auxiliary equipment, additional motors, or to provide a burner interlock switch. Spring returns motor to start position on power failure. Drive shafts located on