Systems and methods of the invention relate to diagnosing a compressor. A method may include operating a compressor to compress air from a first stage compressor into an intermediate stage reservoir, to deliver air from the intermediate stage reservoir to a second stage compressor, and to further compress the air in the second stage compressor into a primary reservoir, monitoring an intermediate stage pressure of the intermediate stage reservoir, and identifying a condition of the compressor through recognition of a change in the monitored intermediate stage pressure during a time period in which the compressor is operated. A vehicle system is also provided including an engine, a compressor operatively connected to the engine, and a controller that is operable to identify a condition of the compressor.