I am a skilled professional that works for a Dor-Mar Heating & Air Conditioning company. I completed a furnace, maintenance, verified air filter to be clean, verified amperage to be good, cleaned off the flame sensor, noted slightly higher ohms on the igniter, and we like to see, potentially indicating failure within the near future. I pulled out the gas manifold, inspected the heat exchanger, and it appeared to be OK. There was slight heat damage, but no cracks or rust. I fired the unit, and the temperature came out good.
