Got a call today about a furnace not working. Went to the residence and the customer explained that originally the burner was working but the indoor fan was not. He had 2 jack-legs give it a shot and now the burner didn't even work. The unit was a Lennox pulse. One of the jack-legs diagnosed it as a bad icm (back when the burner was still working, my guess is because it was shutting off on high limit, who knows?) and replaced it with a cheap generic unit. I first found the wire to the pressure switch loose at the relay, fixed that, when that started sending power to the icm got an error code and traced that to the common and w wires being reversed. switched those around, got the furnace to light and the blower did not start (back to the original problem), which was simply a bad capacitor. His final bill was x. I told him if he had called us first between paying the jack-legs and buying parts he probably didnt need he would have spent about 1/4x. My question for you all is what are some crazy messes you have inherited from other "techs".