So its time to fire up the furnace with the return of winter. The 11-year-old 80% Carrier makes all the normal sounds (first hear the motor for flue venting start, then flame ignites, and finally the blower fan). But wait -- I smell the awful smell of burnt wiring instead of the burnt dust you get after the summer rest. Pretty soon the smoke alarm goes off and the furnace shuts down.
So, I get the smoke alarm to shut off and take the front panel off the furnace and see the burned wires. The tech came out and saw the wires and thought a deeper look necessary. He pulled the blower fan out of the unit -- crawled in its place and found the cracks in the exchanger. I expressed amazement that something much worse could be wrong. So, he went and got his fancy camera with the lense on the end of flexible probe and shows me the crack(s).
So, looking for a second opinion. How likely is it that a cracked heat exchanger could cause the flames to deflect from the horizontal shooting (into the exchanger) and instead go vertical and start burning the wires above??