There is a flush kit you can buy for about $30 (Do a search online for A/C flush kit). You will need an air compressor. It's nothing but a bottle with a T-fiting. One end has an adapter to your air hose (quick disconnect)and the other end has a hose with small rubber tipped nozzle/blower. You fill the can with the cleaner cleaner. Do not use alcohol in the can. If you do, you pretty much have a bomb unless you use an inert gas like Nitrogen. Use either A/C flush solution (about $50) or mineral spirits (about $4) from anystore (Wal-mart has it). One way to make sure all cleaner/flushing material is out of the line or condensor..etc, is to close one end of the line with your thump and intoduce air pressure on the other end. Then, let go your thumb to release pressure. that will push your flush material and dirt out. Repeat it several time until the air coming out feels dry.
Good Luck,

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Meza
1993 190E 2.6
Advanced Diesel Systems Test and Research Engineer