How to flush the old mineral oil and debris out of your classic car A/C system. You must do this when converting from R12 to R134A refrigerant.
Be aware that after a flush, you must blow compressed air through all flushed components to remove any residual solvent. And finally, after reassembling the system, you must apply a vacuum to further remove residual solvent and any air before charging with R134.

Attention! The method in the video is only for old school, tube and fin designs.