Green lines

What causes this - the copper line to turn green? This is a heat pump unit close to the ocean.

Chinese drywall is one cause.

Chinese drywall turn the copper black, not green, although I did not rule that out. Units were built in 2002.

This was the only place in the unit that this has happened. I did check all of the wiring and nothng was black.

That’s right… my bad. sorry about that.

Something has accellerated the corrosion process slightly.

Herre’s the color chart for judging the age of copper by its patina.