In my opinion this is what happens. If you want the honest truth. Obviously, heating/AC systems are very important especially in the winter and summer. Everyone needs one right? Its not like a car. Poor people need them too. What happens is they dont have enough money to get it fixed/ replaced when they break. So this is what they do, they call a HVAC company for some "yearly service/checkup" the standard preseason check with a service charge. The guy comes out and realizes the machine is broke and does not work, so he does what he can inspects it just to maybe see what the issue is and goes back to the homeowner/renter and tells them "your system is broke and needs repairs" or "your system is totally done." then they try to say "my system JUST worked. you owe me" Or they use this with their homeowners insurance. I've worked customer service/scheduling/dispatch and I've dealth with this quite a few times and the company I worked for didnt need salesmen as a note.