You should flush the compressor after replacing the part. The hoses should be thoroughly flushed. Over time, the debris can clog up the condenser and lead to extensive blockage in the tubes. The blockage not only diminishes performance, but it also leads to compressor failure. If you have an older system, you will have an easier time flushing the system if the system contains a serpentine-style tube and fin condensers. You also want to make sure that you have removed all of the debris from the old compressor to prevent the new system from failing.