This is an older furnace but it has always worked fine until this year. I have had it inspected a couple of years ago also along with my upstairs neighbor who had problems and decided to replace her furnace, which was also a Carrier of the same year. I looked at some of the posts and tried cleaning the flame sensor but that didn't change anything. I have tried restarting it a couple of times and the igniter comes on 3 or 4 times and then it shuts down. The sensor is not next to the igniter on this model so I guess there must be some kind of burner that lights to heat up the sensor before the main burners light. Is this sort of what happens? Does anyone have ideas of what could be wrong with this . I am wonder if the Draft Safety switch would cause a problem like this, I don't think there is any problem with the vent , the hot water heater seems to be venting fine through the same pipe but maybe I can check it somehow to make sure a bird didn't fly in there or something. Hope to get this fixed by Christmas , we are have warm weather now but I'm sure I'll want some hear later. Thanks, John