Got two YORK GY9S furnace/air conditioner Tubular Exchanger Series. Our home used to be a duplex. One unit began rattling/shaking and it is getting worse. The feeding pipes are visually shaking when the unit is running the air conditioner. I had the original installer look it over and diagnosed it as the motor and blower pump. I understand this part has a 20year warranty. Is anyone experiencing a similar problem? If so, do you feel diagnosis is correct? Please advise. Thank you.

If the unit is shaking that bad, it sure sounds like a blower motor/blower wheel issue. Main blower components are really the only parts in the unit that could cause it to shake that violently. Sounds like its time to leave it in the techs hands. Should be a fairly easy swap out for a tech, and since its under warranty, let them take care of it. Let us know how things turn out.