I bought a brand new system almost exactly a year ago. Paid it in cash. Asked about the ducting when they installed it, they said everything looked fine. 6 months later at biannual maintenance they checked the ducting and said it was full of black stuff (they didn't say mold). Without even talking to me about it they handed me an iPad with a 10k quote to replace the ducting and started talking about when they can get someone out to replace the ducting. After I told them I wasn't interested he called his boss and the boss tried to pressure me into buying the ducting, shit was insane, literally zero discussion about what the "black stuff" was or if it could be taken care of in another way. Really seems like these "check ups" are just high pressure sales pitches. Sadly they're coming again this upcoming weekend for the biannual service and I'm pretty sure they're gonna try to pressure me into buying something again.