Have the above unit where the draft motor comes on, hot surface lights, and burners ignite. However after about 5 seconds burners go out. This cycle happens twice and then blower comes on.
I believe I have narrowed it down to board or flame sensor. Could this be right??? I checked all `limit switches and all check out OK. I removed flame sensor and cleaned and still no go. Looking at board there are3 LED, 1 yellow and 2 greens. The 2 greens are steady and no fault codes occur. What bothers me is that the troubleshooting sheet on back of cover states that yellow LED is for flame sensor status but this LED never comes on and never blinks as if there is problem.
Should I assume it is the board and replace???