A gas turbine engine clearance control system includes a cooling air passage extending from a cooling air inlet port to a cooling air outlet port. The cooling air inlet port and outlet port are formed within an external surface of a compressor casing of a compressor and are also axially spaced on the external surface of the compressor casing. The cooling air passage extends from the cooling air inlet port radially inwardly to at least one of a flange joint, a radially outer surface of a compressor casing ring, and a radially outer surface of a connector case. The cooling air passage further extends aftward along the radially outer surfaces of the connector case and the compressor casing ring. The cooling air passage further extends radially outward to the cooling air outlet port. Selectively supplying cooling air to the cooling air passage controls a rotor tip clearance between a rotor tip of a rotor blade of the compressor and an inner surface of the compressor casing ring and further controls an interstage seal clearance between an inner band and a rotor spool of the compressor.