on the condenser flush out. you have to disconnect the lines from the reciever dryer, and the input of the condenser, and flush with flushing agent from the reciever connection out the discharge connection. I have not pulled the connections apart on either my parts car or my newly acquired 87TD, so I don't know yet, but be SURE there is no screen, and if there is one, pull it and clean it or replace it. the reciever should prevent any debris from passing it, so the line from the reciever to the evaporator should be clean, but if you get gunk out the condenser, it takes very little time to disconnect the line from the expansion valve to the reciever and flush it as well.
the next thing you have to do is flush from the expansion valve connection of the suction line, through the evaporator out the suction line that goes back to the compressor. this will be harder because the line is larger, and the debris will not as easily be flushed out.
personally, I'd go to a welding supply shop and pick up a 40 or 80C Nitrogen tank and a regulator. to flush it all out. using compressed air will work, but it will also introduce water into the oil residue that is in the lines, and it's nearly impossible to get it out once it's in.