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.