I have a Fridgidaire 90+AFUE furnace that, at times, will start and
stop prematurely. By this I mean that I hear the pilot light start,
then the gas turns on and starts burning, but then the gas shuts off
after 8 or 9 seconds, then finally the blower motor turns on for about
30-45 seconds. This occurs over and over but I have yet to determine
for how long. At first I thought my thermostat was failing (LUX brand)
so I replaced it with a Honeywell - same thing. Is this normal
behavior for a three year old furnace (this being the first winter that
I've noticed the "problem")? I will admit to having done no real
maintenance on this unit since I moved in so if it's a dirty/bad
sensor or something else that's failing then I have nobody to blame
but myself. If its not normal behavior what things can I try to
resolve the problem?