Responded to a no heat emergency for a 20-year-old Amana LP furnace that was blowing cold air and running constantly. Discovered tripped rollout switch. Performed thorough inspection of heat exchanger but could not definitively locate compromise despite checking through blower access and top of unit. CO readings measured at 120 ppm on exhaust with visible black residue on vent pipe. Due to age and safety concerns, recommended immediate discontinuation of furnace operation and provided temporary electric heating while scheduling follow-up for replacement options.
