A heat gun and plenty of penetrating oil does wonders for the connections. They still have a tendency to want to round off, especially on the condenser side since the fitting is aluminum. A good set of wrenches is a must, such as SnapOn FD+ or Proto ASD, anything that bites well on the open end. If the wrench starts rounding off the fitting on the condenser side, a small pipe wrench with good, sharp jaws will bite where everything else just makes it worse. I would suggest heating and spraying the connections several times before you attempt the remove them. Be prepared to buy new lines, if all else fails. Also, try tightening them just a bit before you loosen them, as it can help break the corrosion loose. A big set of flare nut wrenches are ideal, but are rarely found in those sizes without spending big bucks.
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