I don't know how to add much more detail than was given by Dave and James.

The only thing that might not be obvious to those who have not done it, is that all connections are disconnected and the flushing agent is then blown into the components with the flushing device. It is nothing more than a cannister that can be filled with flushing agent, the top screwed back on and then pressurized through a Shrader valve. You then use the blow gun that is attached to the cannister to force the flushing agent into the component. The components are the evaporator, condensor, lines and expansion valve. Flush the compressor with a/c oil, don't use solvent in the compressor.

After flushing each component, use compressed air to TOTALLY blow out ALL solvent. Even a little solvent left in the system can wreck it.

After everything is flushed assemble everything using new o-rings with a/c oil or nylog coated on them. After everything else is connected, put in a new r/d as the last thing, so it will get contaminated with a minimal amount of moisture from the air.

Good luck,