If your induced draft fan is starting but maybe the pressure switch is not making clean the hoses and ports they attcach too see link for what they look like
I don't understand your answer. Are you saying that I should remove and check the sail microswitch? What hoses and ports are you refering to?
I do not see the link you mention.
It seems I will have to pull out the heater core to get at the microswitch, and test it under blower operation. If it does not close, or if it does but the circuit remains open, it seems that I should change the microswitch. I may try that in a couple of days.
If the microswitch tests out ok, then what?
OK, I have the core out.
Micro switch with sail works.
No 24v at yellow and green wires.
110v present at white and blue wires.
No voltage to glow-bar.
Blower comes on with time delay, shuts down with delay.
I reconnected the ignition board, and NOW, after about 90 seconds, the glowbar lights and the burner ignites.
I reinstalled and reconnected the gas, tried it again, but it wouldn't ignite until I tapped on the circuit board. If this happens again, replace the board, right? Sounds like a bad relay on the board. It's a $200 part, so I would like to get it right.
Your answers provided me with little aid in finding my problem. It appears I have a bad connection somewhere, as removing and replacing the core, together with testing the connections, seems to have restored normal operation without actually replacing anything. Ironically, this is something I probably would not have done without you responses being so vague.
I downloaded and reviewed the owners manual and troubleshooting guide, and followed their flowchart. Although I did not pinpoint the exact problem, it gave me actual directions. To the extent that your answers compelled me to do this, they were some help.