Cracked Heat Exchanger: Symptoms, How It's Confirmed and What to Ask For
Signs of a cracked furnace heat exchanger, how a technician confirms one, what to ask for if your furnace is red-tagged, and when to repair or replace it.
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Vadnais Heights furnace repair, including the closet units in its townhomes, starts with a $79 trip charge that we waive when you approve the repair. You get the flat-rate price on paper before any work. We're open 7 days a week, 7am–9pm, and no-heat calls get priority.
Vadnais Heights furnace calls come mostly from 1980s and 1990s two-stories and the townhomes and twinhomes built alongside them. Most houses are on at least their second furnace, often a 90%+ unit, so the failures follow that design: condensate traps that plug and back water toward the pressure switch, cracked pressure switch hoses, inducer motors, flame sensors and igniters. In a cold snap, PVC terminations on the side of a two-story can frost over.
Townhome closet furnaces bring their own problems. Return air often comes through a louvered door, so anything stored against it chokes airflow and trips the limit switch. The water heater may share the closet and its combustion air. Condensate usually drains to a small pump in the same space, and when that pump fails, the furnace stops. Clearances in these closets are tight, and we check them as part of every repair.
Updated September 23, 2026
Every furnace repair call in Vadnais Heights starts with a $79 trip charge, waived when you approve the repair, and a written price before any work. Same prices in Vadnais Heights as in every town we serve. National averages (HomeGuide, 2026), not our prices: a control board $300–$650, an inducer motor $400–$1,100, a PSC blower motor $500–$1,400. More in the furnace repair cost guide.

More detail on our furnace repair page.
Symptom guides: Blowing cold air · Won't ignite · Short cycling · Blinking light codes · Pressure switch trips · Strange noises · Leaking water · Burning smell · Red tag · Carbon monoxide
Sometimes the closet. If the furnace pulls return air through a louvered door, stored boxes or a door kept shut can starve it, and the limit switch shuts the burners off to protect the heat exchanger. A packed filter does the same thing. If the air path is clear, we check the flame sensor, pressure switch and condensate trap, and give you the repair price in writing.
Take a photo of the blink pattern and the code chart on the furnace door; it tells us where the startup sequence stopped. Make sure the filter isn't packed, the switch near the furnace is on, and the PVC pipes outside aren't blocked by snow or frost. Reset the power once, not repeatedly. On the 90%+ furnaces common here, a plugged condensate trap is a frequent cause.
Signs of a cracked furnace heat exchanger, how a technician confirms one, what to ask for if your furnace is red-tagged, and when to repair or replace it.
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Read the guideFurnace repair in Vadnais Heights? Call or send a request.