FLUSHING A/C SYSTEM
There is considerable controversy over the question of whether or not to flush A/C systems or how to go about it. Before CFCs were classified as harmful to the environment, it was a common practice to open flush contaminants from a system. The waste fluid was vented to the atmosphere. This practice is now ILLEGAL and can no longer be used.
Most OEMs don't recommend A/C system flushing. They recommend replacing the defective component and installing a liquid line (in-line) filter ahead of the expansion valve or orifice tube. Ford Motor Company is one exception to this rule.