Cracked Heat Exchanger: Symptoms and How It's Confirmed
Signs of a cracked furnace heat exchanger, how a technician confirms it with a camera and CO readings, what to do after a red tag, and repair vs replace.
Read the guide
Apple Valley furnace repair with us begins with a $79 trip charge, waived when you approve the repair. Many are 1970s split-entries where the furnace still shares the original chimney with the water heater.
A lot of Apple Valley furnaces live in the lower-level utility room of a 1970s split-entry, packed in with the water heater, the softener and often the laundry. That tight space shapes repairs. Shelving blocks the filter slot, dryer lint settles on the burners and blower, and a furnace drawing combustion air from a small closed room can burn poorly. On those chimney-vented 80% furnaces, draft gets checked along with the parts.
The 1980s townhomes are a different setup, with the furnace often in a closet that leaves just enough room to change the filter. Up in the 2000s neighborhoods such as Cobblestone Lake, builder furnaces are now old enough for their first big repairs: inducer motors, pressure switches and control boards, which tend to announce themselves during the first hard cold week.
Updated October 27, 2026
National averages (HomeGuide, 2026), not our prices: a flame sensor $80–$250, a pressure switch $150–$400, a limit switch $100–$375. More in the furnace repair cost guide.
Symptom guides: Burning smell · Red tag · Carbon monoxide · Blowing cold air · Signs your furnace needs a technician
It can. Lint drifts into the burner compartment and blower, and a loose dryer vent pushes lint and moisture into the same small room. Lint on the burners makes lazy flames, and on the blower wheel it cuts airflow until the high-limit switch starts tripping. Keep the dryer vent tight and have the burners and blower cleaned at a tune-up. Manufacturers also warn that bleach and detergent fumes in combustion air corrode furnace parts.
Usually you. In most associations the furnace inside your unit belongs to the owner, but read your governing documents, since some cover exterior condensers or roof vents. We work for the homeowner and give you a written price. If the repair touches an outside wall or roof penetration, we can provide details the association may ask for. Keep a closet furnace's door louvered if it draws combustion air from the room.
Signs of a cracked furnace heat exchanger, how a technician confirms it with a camera and CO readings, what to do after a red tag, and repair vs replace.
Read the guideIs an outdoor wood boiler cheaper than a gas furnace in Minnesota? Fuel math per million BTU, daily labor, smoke rules, freeze risk and backup heat.
Read the guideTrane or Carrier furnace? How the lineups match up, warranty registration windows, quote checks and Minnesota install costs of $4,500–$9,500.
Read the guideHeat out? AC quit? Call or send a request.