Your furnace is about to work harder than it has in eight months.
Right now, in mid-November, Central Indiana temperatures are mild. You’re running your heat occasionally, maybe bumping the thermostat up on chilly mornings. Your furnace turns on, warms the house, and shuts off without issue.
But in six weeks, that same furnace will be running 12-16 hours a day when temperatures drop into the teens and single digits. And that’s when small problems—problems that are developing right now—turn into full-blown emergencies.
The difference between a $150 repair in November and a $5,000 emergency replacement in January often comes down to one thing: catching the problem before the polar vortex hits.
Here are the five furnace issues that seem minor now but become disasters when you need your heat the most—and what you can do about them while there’s still time.
1. The Cracked Heat Exchanger: A Safety Risk Hiding in Plain Sight
What It Is
Your heat exchanger is the component that separates combustion gases from the air that circulates through your home. When it cracks—which happens over time due to repeated heating and cooling cycles—carbon monoxide can leak into your living space.
Why It’s Worse in January
A small crack that barely matters during moderate fall weather becomes a serious problem when your furnace runs continuously in extreme cold. More runtime = more combustion = more carbon monoxide exposure.
Carbon monoxide is odorless, colorless, and deadly. Symptoms include headaches, dizziness, nausea, and confusion—easily mistaken for the flu, especially during winter.
Warning Signs Now
- Yellow or flickering pilot light instead of blue
- Soot buildup around the furnace
- Excess moisture on windows
- Your carbon monoxide detector going off (replace the batteries first, then investigate)
- Rust or corrosion on the furnace or vent pipe
- Strange smell when the furnace runs
What Happens If You Wait
If a cracked heat exchanger fails completely in January, you’re facing an immediate shutdown. Most HVAC technicians won’t—and shouldn’t—let a furnace with a confirmed crack continue operating. You’ll need emergency service when every technician in Central Indiana is likely booked solid.
The November Solution
A pre-winter inspection includes a visual examination of the heat exchanger and combustion analysis to detect problems before they become emergencies. If a crack is found now, you have time to plan for repair or replacement without the pressure of freezing temperatures.
Cost comparison: Scheduled heat exchanger replacement in November or December vs. emergency service call + rushed replacement in January can differ by $1,000-$2,000.
2. The Failing Blower Motor: Two Weeks From No Heat
What It Is
The blower motor pushes warm air through your ductwork and into your home. When it’s struggling—due to worn bearings, failing capacitors, or accumulated dust—it’s living on borrowed time.
Why It’s Worse in January
A blower motor that’s barely keeping up in November will fail completely under the sustained demand of January cold. Motors that cycle on and off a few times a day handle stress differently than motors running 14 hours straight.
The failure pattern is predictable: The motor struggles, overheats, and eventually seizes or burns out entirely.
Warning Signs Now
- Furnace runs but little to no air comes out of vents
- Weak airflow compared to previous years
- Screeching, squealing, or grinding noises when the furnace runs
- Furnace cycles on and off frequently (short cycling)
- Burning smell when the system starts
- Significantly higher electric bills (motor working harder draws more power)
What Happens If You Wait
When a blower motor fails in January, you have zero heat until it’s replaced. In a best-case scenario, you may be without heat for 24-48 hours. In a worst-case scenario during peak demand, you could be waiting 3-5 days for parts and service.
That means hotel bills, frozen pipes, or huddling around space heaters—none of which are cheap or comfortable.
The November Solution
A technician can test the blower motor’s amp draw, listen for bearing noise, check the capacitor, and assess remaining lifespan. If your motor is failing, replacing it now means:
- Scheduled service at standard rates (not emergency pricing)
- Your choice of appointment times
- Parts readily available
- Work completed in a few hours
3. The Ignition System on Its Last Leg: It Fails When You Need It Most
What It Is
Modern furnaces use either hot surface ignitors or electronic ignition systems to light the burners. These components wear out over time—typically after 3-7 years of use—and when they fail, your furnace won’t produce heat.
Why It’s Worse in January
Ignition systems fail most often during cold snaps because:
- They’re cycling more frequently
- The components are under maximum stress
- Older ignitors become brittle and crack more easily at temperature extremes
You don’t get warning signs spread over weeks. One day it works. The next day it doesn’t.
Warning Signs Now
- Furnace tries to start but fails (you hear the click but no flame)
- Multiple attempts to ignite before it catches
- Furnace shuts down shortly after starting
- You smell gas but the furnace doesn’t light (call immediately if this happens)
- Ignitor glows but burners don’t light
- Furnace works fine for days, then randomly fails to start
What Happens If You Wait
An ignition system failure in January means no heat until a technician can replace the component. The part itself is relatively inexpensive ($50-$200), but getting someone to your house during a cold snap is the challenge.
Hot surface ignitors are fragile. If yours is over 5 years old and showing any signs of struggle, it’s on borrowed time.
The November Solution
During an inspection, a technician can visually examine the ignitor for cracks or wear and test its performance. If it’s marginal, replacing it now is cheap insurance against a January failure.
Many technicians recommend replacing ignitors proactively at the 5-7 year mark simply because the cost of failure (being without heat) far outweighs the cost of the part.
Cost comparison: Preventive ignitor replacement: $150-$300. Emergency service call + replacement on a 15°F night: $350-$600.
4. The Clogged Condensate Line That Freezes: A Uniquely Indiana Problem
What It Is
High-efficiency furnaces (90%+ AFUE) produce condensation as they operate. This moisture drains through a condensate line, typically running to a floor drain or sump pump. When that line gets clogged with algae, mold, or debris, water backs up.
Why It’s Worse in January
Here’s the Indiana-specific problem: condensate lines often run through unheated spaces—crawlspaces, exterior walls, or garages. In moderate temperatures, a partial clog is just an annoyance. In January cold, that standing water freezes solid.
A frozen condensate line triggers safety switches that shut down your furnace completely. And you can’t just thaw it and restart—the underlying clog needs to be cleared.
Warning Signs Now
- Water pooling around the base of your furnace
- Furnace shuts down randomly, then restarts after sitting
- Gurgling sounds from the condensate drain
- Visible algae or slime in the condensate trap
- Musty smell near the furnace
- Frequent need to reset the furnace
What Happens If You Wait
A frozen condensate line in January means:
- Your furnace shuts down for safety
- The line needs to be thawed (which takes time in freezing conditions)
- The clog must be cleared
- If the line froze hard enough, it may have cracked and need replacement
This is a multi-hour repair during the time you most need heat. And if the line cracked, you’re looking at more extensive work.
The November Solution
Condensate line maintenance is simple and cheap when done preventively:
- Clear any existing clogs with compressed air or shop vac
- Flush the line with vinegar or condensate pan tablets
- Insulate exposed sections of drain line
- Ensure proper slope for drainage
- Add a safety float switch if one isn’t present
Cost comparison: Preventive condensate maintenance: $75-$150 (often included in tune-up). Emergency frozen line service: $250-$500+, plus potential line replacement.
5. The Thermostat That Can’t Keep Up: Wiring Issues vs. Equipment Failure
What It Is
Your thermostat is the brain of your heating system. When it malfunctions—due to faulty wiring, dead batteries, dust accumulation, or calibration drift—your furnace doesn’t get the right signals about when to run.
Why It’s Worse in January
Thermostat problems often appear minor in mild weather. The house is a degree or two off target? You throw on a sweater. But when it’s 8°F outside and your thermostat thinks it’s 72°F inside when it’s actually 64°F, you’ve got a serious problem.
Additionally, some thermostat issues only appear under sustained load—when the furnace is running long cycles repeatedly.
Warning Signs Now
- Temperature swings greater than 3-4 degrees
- Furnace doesn’t turn on when it should
- Furnace runs constantly without reaching setpoint
- Thermostat display is blank or flickering
- Incorrect temperature reading (compare to a separate thermometer)
- Furnace doesn’t respond when you adjust temperature
- Recently replaced batteries but still having issues
What Happens If You Wait
Here’s the tricky part: thermostat problems often get misdiagnosed by homeowners as furnace problems. You think your furnace is broken when it’s actually just not receiving the right signals.
This leads to unnecessary service calls, frustration, and the potential for your furnace to short-cycle (turn on and off frequently), which causes premature wear on components.
In the worst case, a thermostat with bad wiring can cause your furnace to run continuously, spiking your energy bills and potentially overheating components.
The November Solution
A pre-winter inspection includes thermostat testing:
- Verify accurate temperature readings
- Test heating and cooling signals
- Check wiring connections for corrosion or looseness
- Assess battery condition (even hardwired thermostats often have backup batteries)
- Test all programmed settings
- Determine if the thermostat is properly located (away from drafts, direct sunlight, heat sources)
If your thermostat is more than 10 years old, upgrading to a programmable or smart thermostat now—before winter—can improve both comfort and efficiency.
Cost comparison: Thermostat replacement (scheduled): $150-$400. Emergency diagnostic call to discover it’s “just the thermostat” when you thought it was the furnace: $150-$200 for the call, plus thermostat replacement.
What a Pre-Winter Inspection Actually Catches
You might be thinking: “Do I really need someone to look at my furnace if it’s working fine?”
Here’s what Central Indiana homeowners often don’t realize: most furnace failures are predictable. The components don’t just suddenly die—they show signs of wear, inefficiency, or degradation that professionals can spot.
A thorough pre-winter furnace inspection includes:
Safety Checks:
- Carbon monoxide testing
- Gas pressure testing (for gas furnaces)
- Heat exchanger inspection
- Flame sensor condition
- Vent pipe integrity
- Gas valve operation
- Safety switch functionality
Performance Testing:
- Temperature rise measurement (how much the furnace is heating the air)
- Airflow assessment
- Blower motor amp draw
- Burner flame pattern
- Ignition system operation
- Thermostat calibration
- Filter condition and sizing
Preventive Maintenance:
- Clean burners and flame sensor
- Lubricate blower motor (if applicable)
- Clear condensate line
- Tighten electrical connections
- Test capacitor
- Inspect belts (older systems)
The Information That Matters:
A good inspection doesn’t just tell you “everything’s fine” or “you need a new furnace.” It tells you:
- Which components are nearing end of life
- What to watch for over the winter
- Whether repairs make financial sense vs. replacement
- Your expected energy efficiency compared to baseline
- Whether any safety issues require immediate attention
This information lets you make informed decisions on your timeline, not in a panic at 11 PM on a Saturday in January.
When to Repair vs. When to Replace
This is the conversation nobody wants to have, but it’s the most important one.
Not every furnace problem should be repaired. Sometimes the right answer is replacement, and a November inspection is the perfect time to have that honest conversation.
The Age Factor
Furnaces under 10 years old: Almost always worth repairing unless there’s catastrophic failure Furnaces 10-15 years old: Depends on the repair cost and overall condition Furnaces over 15 years old: Repair costs over $1,000 often don’t make financial sense
The 50% Rule
A common industry guideline: If the repair cost is more than 50% of replacement cost AND your furnace is past the midpoint of its expected lifespan, replacement is usually the smarter investment.
Example:
- Your furnace is 13 years old (expected lifespan: 15-18 years)
- Heat exchanger replacement cost: $2,500
- New high-efficiency furnace installed: $4,500
- Repair is 55% of replacement cost + furnace is 70%+ through its lifespan = Replace
Red Flags That Mean “Replace, Don’t Repair”
- Cracked heat exchanger on a furnace over 12 years old – This is the big one. Heat exchangers are expensive to replace, and if yours is cracked on an older system, replacement almost always makes more sense.
- Frequent repairs – If you’ve spent $800+ on repairs in the past two years, you’re likely entering the “repair spiral” where one component fails, you fix it, another fails, repeat.
- Energy bills creeping up – An aging furnace loses efficiency. If your gas bills have been steadily increasing despite similar usage, your furnace is working harder to produce the same heat.
- Uneven heating – Rooms that are consistently too hot or too cold despite thermostat adjustments often indicate a furnace that’s either oversized, undersized, or failing.
- Constant cycling – Short-cycling (turning on and off frequently) damages components and signals a furnace that can’t regulate properly.
- You’re facing a major repair on a system that’s already inefficient – If your 16-year-old 80% AFUE furnace needs a $1,500 repair, you could put that money toward a 96% AFUE system that’ll cut your gas bills by 20%+.
The November Advantage for Replacement
If your inspection reveals that replacement makes more sense than repair, November is the ideal time to do it:
- Tax credits still available – Remember that federal tax credit we talked about? It expires December 31, 2025. A furnace replacement in November still qualifies.
- Better scheduling – HVAC contractors aren’t slammed in November. You get your choice of dates, not “we can squeeze you in next Thursday.”
- Time to shop – You can compare options, get multiple quotes if desired, and make an informed decision. No pressure, no emergency.
- Test before you need it – Install in November, run it during moderate weather to ensure everything works perfectly, then you’re confident when January cold hits.
- Standard pricing – No emergency fees, no rush charges, no premium for same-day service.
The Real Cost of Waiting
Let’s talk numbers.
Scenario 1: The Preventive Route
- November furnace tune-up: $129-$179
- Minor issue caught and repaired: $200
- Total: $329-$379
- Result: Furnace runs all winter without issue
Scenario 2: The “Wait and See” Route
- No inspection, furnace seems fine
- Blower motor fails January 15 at 6 PM when it’s 10°F outside
- Emergency after-hours service call: $150-$250
- Blower motor replacement with emergency premium: $900
- One night in hotel while waiting for morning appointment: $150
- Total: $1,200-$1,300
- Result: 18 hours without heat, significant stress, much higher cost
Scenario 3: The “Complete Failure” Route
- No inspection, ignoring warning signs
- Heat exchanger cracks in late December
- Emergency diagnosis: $150
- Told furnace cannot operate (safety issue)
- Need immediate replacement
- Limited options due to emergency timeline
- Emergency furnace installation: $5,500 (vs. $4,200 scheduled)
- Portable heaters for two days: $100
- Total: $5,750
- Result: Forced into replacement at the worst possible time, paying premium pricing
The math is clear: preventive maintenance costs a fraction of emergency repairs, and exponentially less than emergency replacement.
What You Should Do Right Now
If your furnace is more than 5 years old, hasn’t been inspected in the past year, or is showing any of the warning signs mentioned in this article, don’t wait.
Option 1: Schedule a Pre-Winter Inspection
Call Absolute Comfort at (765) 534-4328 to schedule a comprehensive furnace safety and performance inspection.
What you’ll get:
- Complete safety inspection including carbon monoxide testing
- Performance assessment and efficiency measurement
- Identification of any components nearing failure
- Clear explanation of findings in plain language
- Honest recommendation on repair vs. replace
- Written report you can keep for your records
- Upfront pricing on any recommended repairs
Typical inspection time: 60-90 minutes Cost: $129-$179 (often waived if repairs are needed)
Option 2: If You’re Already Having Issues
If your furnace is showing symptoms of any of the five problems listed in this article, don’t schedule a routine inspection—call for service now.
Call (765) 534-4328 and mention the specific issue you’re experiencing. We’ll prioritize diagnosis and repair before winter demand hits.
Option 3: If Your Furnace Is Old or Unreliable
If you know your furnace is nearing the end of its life, or you’ve had multiple repairs in recent years, schedule a replacement consultation now—while you still have time to make a good decision.
Benefits of scheduling now vs. waiting:
- Still eligible for 2025 federal tax credits (expires Dec 31)
- Better equipment selection and availability
- Flexible installation scheduling
- Time to explore financing options
- Standard pricing, not emergency rates
Save Our Emergency Number
Even with the best preventive maintenance, emergencies can happen. Save this number now before you need it:
Absolute Comfort Emergency Service: 765-534-4328
We offer 24/7 emergency service throughout Central Indiana because we know furnace failures don’t wait for business hours.
The Bottom Line
Your furnace doesn’t care that it’s Thanksgiving week or Christmas morning. When a failing component gives out, it gives out—usually at the worst possible time.
The five problems in this article are developing in furnaces across Central Indiana right now. The difference between homeowners who have heat all winter and homeowners who face January emergencies comes down to one decision: acting now while there’s still time.
A November inspection costs $129-$179.
An January emergency costs $1,200-$5,000+.
The choice is obvious.
Don’t gamble with your family’s comfort and safety this winter. Call Absolute Comfort today at (XXX) XXX-XXXX to schedule your pre-winter furnace inspection.
Your future self—warm and comfortable in January—will thank you.
Absolute Comfort provides comprehensive furnace inspection, repair, and replacement services throughout Central Indiana. Our licensed, experienced technicians prioritize safety, transparency, and customer education. All service calls include upfront pricing and clear explanations of findings. Emergency service available 24/7.