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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Builder furnaces in Lakeville break like any others, and our repair terms are simple: a $79 trip charge that's waived when you approve the fix, and a flat price in writing before we start, any day from 7am to 9pm. Some newer furnaces here are still under the manufacturer's parts warranty.
Lakeville furnace calls come in two waves. The 1970s and 1980s homes near downtown and around Lake Marion and Orchard Lake are on their second or third furnace, often a 1990s or 2000s unit with worn inducer bearings, cracked igniters and tired blower motors. The post-1990 subdivisions, and the new construction still going up, have 90%-plus furnaces venting through PVC, an air exchanger and long duct runs.
In the newer homes, many no-heat calls are drainage: a condensate trap packed with construction debris, a drain line that wasn't pitched right, or a condensate pump that failed and tripped the safety switch. Bonus rooms over garages run cold because the duct run is long and passes through a cold space, and a furnace repair alone won't change that. On newer equipment we check the registration and warranty status first, because a covered part can change what you pay.
Updated September 23, 2026
Every furnace repair call in Lakeville starts with a $79 trip charge, waived when you approve the repair, and a written price before any work. Same prices in Lakeville as in every town we serve. National averages (HomeGuide, 2026), not our prices: a PSC blower motor $500–$1,400, a variable-speed (ECM) blower motor $800–$2,300, an igniter $100–$250. 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
It depends on the warranty paperwork. Many manufacturers give the longer parts warranty only when the equipment was registered online within 60 days of installation, so check registration with the model and serial numbers from the label. A covered part leaves you paying labor only. Builders' own workmanship warranties are usually short, so read yours. We'll tell you what the part costs either way before we start.
A 90%-plus furnace makes water all winter, and it has to reach a drain. The common causes are a trap clogged with debris, a drain line without enough slope, a cracked fitting or a failed condensate pump. A whole-house humidifier on the furnace can also leak. Put a towel down, check whether the pump runs when you lift its float, and call us. Left alone, a flooded trap shuts the furnace off.
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.
Read the guideFurnace quit in a cold snap? How to tell if the PVC intake or exhaust is iced or drifted shut, clear it without cracking the pipe, and keep it from recurring.
Read the guideA furnace that turns on and off too often tells you what's wrong by how long it runs. How to time a cycle, and what seconds, minutes and frequent cycles mean.
Read the guideFurnace repair in Lakeville? Call or send a request.