The owners of the house next door are elderly, it's her Parents house, it's really their storage facility as they live in a high end retirement community. They have the HVAC serviced twice a year by a "reputable" company. Last year I was there when the tech showed up, she immediately claims the coil is cracked, and they need a new system. Granted the system is about 20 years old(air handler/coil) and the outside unit is about 10 years old. Since cooling season was over we told the Tech we would deal with it this year. Fast forward to a couple of months ago, house had a frozen water line burst from the cold in February, repairs were being completed, AC had been running a couple of weeks with no issues. The new Tech comes in to tell the Owner and I that there is NO refrigerant in the system, likely due to the cracked a-coil. He went into great detail to describe the little valve in the line that he pushed and nothing came out, I told him it was a Shrader Valve. He proceeded to tell us the system was old and needed to be replaced, they had a super special offer to replace the system, and do regular maintenance calls for 10 years, for only $200 a month, it's a 2000sq ft single story home, that's $24K for the system, and maintenance(no parts/labor, just clean and inspect twice a year).
I told him it was odd that the system had been keeping the house cool during the repairs with no issues, and that it was actually running and cooling right now. He walked off looking puzzled...
A bit later he comes in, tells us he really screwed up, his "gauges" are blue tooth, and they were still set to the last house, the system in fine, no issues, running perfectly. Then he spent another 10 minutes trying to talks us through the deception we caught him in, and how it was really just an honest mistake, but we really should consider replacing the system as it is old, he should have just walked.
The system continues to work just fine, through several 100 degree days, and many days in the 90's. It will have issues eventually, they will have to decide then what to do, and have the new service company bid on it.
What really concerns me is if I hadn't been there, the Owners would have jumped on the new system with no hesitation, they are in their mid 80's and would have believed the Service Tech. Unfortunately there are probably many folks that get suckered into these deals.