Abstract: An air conditioning system including an air flow limiter and indicator comprising, in combination: a chamber (24) extending from an inlet (21) to an outlet (22) for flow therebetween of conditioned air at greater than ambient pressure; a damper (63) in the chamber actuable to variably restrict the flow; apparatus outside the chamber, including an inflatable member (66) having inlet (70) and venting (42) openings, for actuating the damper in accordance with the state of inflation of the member; condition-responsive apparatus, including a fluid amplifier (72) supplying fluid from the chamber to the inlet opening, for causing inflation and deflation of the inflatable member; apparatus including a vane (32) in the conduit for responding to the rate of flow of the fluid in the conduit; apparatus (41, 57) normally closing the venting opening; and apparatus (43, 45, 55) operable by the vane as the rate of flow exceeds a predetermined value for unclosing the venting opening, to enable deflation of the inflatable mean