I haven't called anyone for service yet as this is a puzzler and I want to try to solve it before I give up.
The flames are blue, steady with minimal yellow flicker. The furnace recieves plenty of ventilation, it's in a basement washroom which has an air vent in the wall. When the blower comes on the flames don't change just stay a steady blue. The rollout switches are manual but don't have to be reset when it starts up and runs normally. The rollout switches are all replaced and are new. It does give the 5 flash error code. The error will sometimes occur immediately right after I apply power well within 1 second, before the furnace even starts up. I don't see how it has time to sense anything at that point. Flipping the power off then back on it may error out 6 t0 10 times then start normally and run fine for a few days then may not work correctly for 2 days.
Another thing of note, I always here what sounds like a relay opening on the control board before the error occurs and the furnace shuts down. Don't know if this is normal or not because maybe if the furnace does since a problem the relay is supposed to open or could it be faulty? I don't know.
