I have a 20+ year old 95% FUE Comfortmaker which just started to act up. It heats the house, then goes into a 'lockout' mode in which the computer blinks continuously and the fan runs at full tilt. Book says to cycle the power. It starts and runs normal after that until things warm up. The blink code is supposed to mean 'flame sensed with no call for heat' which doesn't mean crap to me. All the other blinker codes indicates some real problem (pressure switch, grounded condensate, etc). Anyways, I pulled out the flame sense switch and cleaned it, no effect. Checked for water in the condensate trap (you MUST have some in there for it to work, but not excess), no effect, and then pulled out the heat limit switch. It was a bit charred and disintegrated when I softly removed it. New one was $15. from a parts guy down the street but new ones on internet can be $150. Put the new limit switch in and it fired right up no further problems.
Furnace part guy told me that a lot of the new super allergen filters are causing furnace problems because they restrict the airflow too much causing an overheat situation. That can tax the limit switch & surrounding material properties. I changed the filter, too, BTW.
Just thought I'd pass on this information. The charring on the limit switch and wiring made me concerned about fire possibilities.
That's all folks !!
Furnace part guy told me that a lot of the new super allergen filters are causing furnace problems because they restrict the airflow too much causing an overheat situation. That can tax the limit switch & surrounding material properties. I changed the filter, too, BTW.
Just thought I'd pass on this information. The charring on the limit switch and wiring made me concerned about fire possibilities.
That's all folks !!