Abstract: A method for removing deposits from at least one compressor powered by an engine. The method comprises disconnecting while the engine is turned off, a high pressure downstream side of the compressor from an intercooler, or an air intake manifold for non-intercooled engines, while leaving the compressor attached to a means used in the engine to drive the compressor. The output airflow is diverted from the compressor away from the engine to a disposal or to a means of separating a cleaning fluid from air. After starting the engine and while the engine is running, the cleaning fluid is injected for a sufficient time to clean the compressor.