I noticed this weekend furnace will come on , then the flame starts and then blower for the house starts. After a few minutes flame goes out fan still is on because the thermostat in house has not been satisfied, flame comes back on, and then it happens again. So this takes place three times before the thermostat is satisfied, flame on then off, on then off, on then off, and the it cools down and shuts off,until the thermostat requests heat again. The furnace is a comfortmaster, 100,000btu for a 1500sq ft house. It was in house when we bought it in april. The furnace is around a 2000 model. Had a teck come out he thought furnace was too big for house, so he set the fan for high speed, heat and air cond. Also checked the a switch that was in the fir box, I think a switch that sinces heat in the box. He said that it was alright. He thought furnace was to big for house, and getting to hot in fire box cycling off and then on again. After setting high fan it only cycled two time instead of three times. So I was looking for another opion. Any more info needed, let me know. Sorry for lenth.