Until purchasing my own country home a few years ago, I lived in a large ci ty and always rented. I have almost zero mechanical skills. Now that I've retired and my income pared by 66%, I need to learn to do many a repair th at until now fell to others.
In the case of the furnace not firing, I called the local HVAC repair peopl e. The technician was puzzled. As he fiddled around with the main switch a ffixed to the side of the furnace, the unit fired. He assumed there was a short in that switch and after cutting power to the unit, proceeded to swap out the switch with a new one. When power was restored, the unit continued not to fire when called upon to do so. He then removed a cover panel that exposed a circuit board (Honeywell ST9103A). He poked at a wiring harness that is connected to the board (harness attached in upper right of board in photo linked below) and by wiggling same, the unit fired. Jiggling the ha rness resulted in the unit kicking on and off, on and off, in "fits and sta rts" as if there were a faulty connection somewhere. He positioned the har ness in such a way as to ensure the unit would fire (at least at that time) , replaced the cover panel, and wrote me a bill for $164. The bill read "f ound there to be a loose connection on wiring harness, corrected problem, u nit running well."
While I can't argue with his assessment of the situation, I've learned to p oke around a little myself next time before making a phone call that I know will result in a minimum $85 just for the call.
With that said, this morning the unit failed once again to fire. I accesse d the panel myself and by wiggling the wiring harness, all systems are agai n GO. What is the long-term fix here? Do I attempt to replace the board ( $80 for a replacement)? Do I purchase a new wiring harness and replace tha t? Both? Is either job very complicated? Thanks in advance for any assis tance.