"Flossing" the AC hoses. Even after repeated flushes I could still find evidence of residue. I used some synthetic clothesline rope and blew the rope through the lines with compressed air. For the larger diameter high pressure hose I sent the rope from end to end, tied a knot, and pulled the knot through to help scrub the inside. Once I had a complete length through the hose, I soaked it in AC flush solvent and pulled the rope from end to end several times. A final flush was then performed with the rope removed. I did this process only on the HP and condensor crossover hoses. The low pressure line is after the orifice valve filter and the dryer and was much cleaner.