This is super common in my area, only on Heritage buildings. They dont want unsightly condensors on the ground near the building, so theyre either in the attic, or the basement. Seen both. 😆
Alot of times this is cause by dirty coils and or a clogged condensate line water build up keeps cooling and once it freezes it grows into a iceberg it can destroy a until if not caught in time
I'm gonna guess this was in concrete? I'm sure you know what the lime in concrete does to copper. I'm sure that if it's been there long enough, the lime will eat that, too. Glad my gas shit was replaced recently
I always tell people in my line of work if you think a $60 oil change was bad a new engine is gonna cost $6 grand oh and that's just for the long block not including my labor at $200/ hr . I suppose this is a similar circumstance.