buetler heating and air disabled heating unit during inspection sacramento California

I am a handyman. Last fall I was called by a client to do some work. As I was finishing she asked if I knew anything about a.c. Units. I do so I told her I would look at it. She had called for a serviceman and he was supposed to be there that afternoon. She said that she had paid for a service at the beginning of summer to inspect it and get it ready for winter. I looked in the unit and saw that it was flashing a code that meant it wasn't getting gas. This was a Lennox unit, and it had a very small on and off switch on the gas valve and it  was off. I switched it on and the unit fired up. My client told me that when the tech, came to clean the unit he told her that the it was on its last legs as it was ten years old. She cancelled the service call, although I would have liked to see how it turned out. I just figured it would lead to ninety dollar charge.