Sabotage
From what I know, the vast majority of residential HVAC units are/were made in Indiana.
It is, or was, the largest HVAC factory in North America, after UTC consolidated all of Carrier and Bryant's capacity.
Those workers are PISSED. I would not trust a large necessary machine coming out of that factory anymore.
I worked for UTC for a while.
They actually are a great employer, until the day they don't need you.
I saw a management presentation once on accident.
All the rest of us "little people" were literally described as "engineering energy" and that ENERGY can be transferred wherever and whenever they see fit.
That was the day I knew I had to leave.
Not that the grass is ever much greener elsewhere.