I have a comfortmaker furnace(n8mpn075b12b1).The furance is about 8 years old.The problem is,the furnace will run OK for 4 to 6 hours OK and then it will come on,combustion blower starts,igniter,then gas,burner comes on for about 5 seconds then shuts off.Will do this about three times,then shuts down.On the control board the led will blink 6 times then pause, then repeat.I can turn the power off and then back on and the furnace will work again for a while.Over night the furnace shut down,this time on the control board,the led blinked 6 times pause then 1 time pause and kept repeating.Again turned the power off and on.Waited about 10 seconds in between off and on.The furnace run OK heated up to 72 degrees.