Finding Where a RAG Answer Went Wrong

A technician at a customer's home asked the repair guide assistant: "On the GF-80 gas furnace, what does three flashes of the status light mean?" The assistant answered that the pressure switch had not closed, told the technician to check the vent pipe, and cited the GF-60 service manual. In the GF-80 manual, three flashes means the flame sensor did not detect a flame.

The technician replaced a pressure switch that was working, and the furnace still would not start. A second visit the next day found the real fault