Exemplary embodiments of a system and method for bimodal air control in a kettle-style grill are configured to be detachably mounted to the exterior of a kettle-styled grill such as, but not limited to, a Weber® charcoal grill. When mounted to the kettle-styled grill, a plenum-like component directs air flows to the interior of the grill's kettle via the kettle's lower body damper holes. A manually adjustable intake damper in the plenum component allows, restricts, or prevents a drawn ambient air flow into the plenum component. Separately, a forced air flow generated by a fan may also be provided into the plenum component. Adjustment of the intake damper may also adjust damper blades inside the grill's kettle. Ash that falls out of the kettle's damper holes falls through the plenum component and is captured in an ash receptacle that is removably mounted to the plenum component.