Hanlon's Razor: "Never ascribe malice to that that can be explained by simple stupidity"But would he have just simply have plugged in the HVAC unit for $600 or would he charge her for a new one as well?
Mechanics an be crooks.
My neighbors sister was charged $50 to replace her blinker fluid.
He went to the shop and said if you don't give her her money back, I'm phoning the cops
I don't think that he would have done that, Rona has been going to his shop for years with no issues.
Remember, most mechanics -specially the older generation- are not that well versed in electronic troubleshooting.
I work on the principle of Occam's Razor: "The simplest explanation is usually correct".