a bypass control system and method monitors and controls the amount of air recirculated through a bypass duct from the air supply outlet supplied by a fan and motor from a single zone hvac unit to the air intake thereof , a stepper motor driven bypass damper is located in the bypass duct having a damper blade movable between opened and closed positions and intermediate positions therebetween , and a bypass monitor is connected to the bypass damper for controlling the operation of the stepper motor of the bypass damper . a first amperage sensor is looped around the common lead of the motor and the monitor provides information indicative of the amount of work performed by the motor to the monitor , the motor performing less work when static air build up occurs at the outlet due to closure of dampers in the duct system conditioning air to a plurality of zones , and the monitor causes the bypass damper to open to correspondingly compensate for the static air pressure build up by reducing same and causing more air to be recirculated through the bypass duct to maintain the air pressure supplied by the hvac unit to the duct system generally constant .