Called Elm with "Furnace not providing heat as main burner does not ignite" at noon. They said a technician would arrive by 4pm. The technician arrived at 3:15. He examined the furnace and used the computer board to diagnosis the problem. When the computer board did not provide the cause, he placed a call to the furnace company. While waiting for the furnace company to answer his call, he continued to diagnosis the furnace. He found the problem, a stuck pressure switch. The furnace is working. I was left with a recommendation of replacing the pressure switches as the high fire pressure switch may get stuck again.
more