Quote Originally Posted by Al Willits
When you said in your first post the pilot wouldn't light, was it the pilot or the main burner??
Pilot.

The way the thing normally works, is that the thermostat will give a click, and the yellow "system" LED will light. This causes the furnace to light, and 10-30 seconds later you hear the muffled "whump" as the main burner kicks in. Then another 30-60 seconds(?) after that the fan kicks in.

(I know, you know all this... )

With my problem yesterday evening, the thermostat would give the initial click, but then immediately give another click, so what I'd hear would be "click-click". The display would blink at the same time, and then nothing would happen for about 20-30 seconds and then it would try again. (so the system light did NOT light up.)

thanks again, Al.