I asked about this once already however I have done more troubleshooting and am going NUTS. I have two of these colemans mine and the one in My fathers home. The one In Dad's house clicks on and the blend air fan comes on for approx 30 seconds then the igniter heats up and we have A flame... for 30 seconds then the blower kicks on and the flame goes out, it will go through this twice more then quit. I originally discovered that the attic fan was toast and replaced it thinking the problem would be solved, Not so. I cleaned and later swapped the flame sensor with the one in my furnace, Nothing... I swapped out the control board as well, Still Nothing. Mine still works fine with the parts from the problem furnace, the only difference is that after 30 seconds of flame the offenders blower motor comes on and the flame goes out. Mine is A Red T Blendair 2 The offender is A Deluxe Blendair 2, I even tried removing the wires to the attic fan , Nothing. HELP PLEASE.

Patients is a virtue!! One I have trouble with, I have gone through EVERYTHING on this, A short time ago I tried bypassing the limit switches and as always after about 30 seconds of flame the fan came on and the flame went out... I was leaning... in exasperation, against the fan housing and noticed that it ran longer than it did at the start of this odyssey and then I saw the orange glow from the igniter and shortly a flame again. Every other time I checked this after I replaced the attic fan I siply switched off the power inside the furnace because it was acting exactly as it had when it did not work. At least this has taught me SEVERAL valuable lessons in D.I.Y. # 1 Don't take anything for granted.