Furnace Repair Costs
what the real numbers look like for every common fix
So you know what's fair before the tech walks in the door

Your furnace stopped working at 11 p.m. on a Tuesday in January. You called an HVAC company, and now you have a quote in your hand with a number that may or may not be reasonable—and no fast way to know. That information gap is exactly what this article closes.

What follows is a repair-by-repair breakdown of what each common furnace fix actually costs, why the price is what it is, what drives it higher or lower, and when a repair stops making financial sense. These are real-world ranges drawn from contractor invoices and industry cost surveys, not inflated estimates designed to make a replacement sale look attractive.

Service Call and Diagnostic Fees: The Starting Point

Before any part is touched, you pay for a technician to show up and figure out what's wrong. Most HVAC companies charge a diagnostic fee between $75 and $150, and a few charge as high as $200 in high cost-of-living markets like San Francisco or Boston. Some companies waive this fee if you proceed with the repair; others don't. Ask before you book—this matters when you're getting competing quotes.

After-hours calls—evenings, weekends, and holidays—typically add a surcharge of $50 to $100 on top of the base diagnostic fee. If your heat fails on a Saturday night in December, expect to pay toward the top of that range just to get someone there. That's not gouging; that's the real cost of emergency availability.

One thing worth knowing: the diagnostic fee is real labor. A competent technician spends 30 to 60 minutes running the furnace through its startup sequence, reading error codes, checking pressures and temperatures, and probing electrical connections. The technicians who skip this and guess at parts are the ones who end up replacing the wrong component and charging you again. A thorough diagnostic is worth the fee.

When you get a quote that includes both the diagnostic and the repair on the same invoice, confirm whether the diagnostic charge is being absorbed into the total or added on top of the parts and labor estimate. It's an easy place for quotes to look artificially close when they aren't.

Igniter Replacement: The Most Common Fix of All

If your furnace is running—the blower kicks on, you hear a click—but no heat comes out, a failed igniter is the first suspect. Hot surface igniters are ceramic elements that glow orange-hot to light the gas, and they fail more often than any other single furnace component. On most residential furnaces, the part costs $20 to $80, and the total installed price with labor runs $100 to $250.

The wide range comes down to furnace brand and model. A Lennox G61MPV uses a specific Lennox-branded igniter that lists for around $65; a Carrier 58MVC uses a different style that can be had for $25 from a wholesale supplier. Labor is usually under an hour because the igniter is almost always accessible without disassembly—it's a straightforward swap.

Some technicians will upsell you to a silicon nitride igniter if your furnace currently uses the older silicon carbide style. Silicon nitride igniters are genuinely more durable and crack less easily when handled. The upgrade costs roughly $30 to $50 more than a like-for-like replacement and is probably worth it, especially on a furnace that will run another 5 to 10 years.

One failure mode people miss: sometimes an igniter isn't actually broken—it just has a loose wiring connection or a cracked porcelain housing that makes it arc improperly. A good technician will check both before ordering a part. This matters because a new igniter installed with the same bad wiring will fail again in weeks.

Blower Motor and Capacitor: When the Fan Is the Problem

The blower motor moves heated air through your ducts. When it fails, the furnace may fire normally but your house gets no warm air, or the system short-cycles because the heat exchanger overheats without airflow. Blower motor replacement is one of the pricier repairs: expect $300 to $600 total, with parts running $150 to $350 and labor adding another $100 to $200.

Variable-speed blower motors—the ECM (electronically commutated motor) type found in higher-efficiency furnaces like a Trane XV95 or a Carrier Infinity series—cost considerably more. Parts alone for an ECM module can run $400 to $600, pushing the total repair to $600 to $900 or more. ECM motors are more efficient and quieter, but they're also significantly more expensive to replace.

Before blaming the motor itself, a technician should check the run capacitor. The capacitor gives the motor the electrical boost it needs to start and stay running, and it fails far more frequently than the motor does. A capacitor costs $10 to $30 as a part, and replacement is usually billed as a flat charge of $75 to $150 installed. If a tech immediately jumps to quoting a blower motor without checking the capacitor, that's worth questioning.

The diagnosis is usually straightforward: if the motor hums but doesn't spin, the capacitor is the likely culprit. If the motor doesn't respond at all or smells burned, the motor itself is probably done. Amperage readings taken by the tech during startup will confirm it either way.

Labor time for a blower motor swap varies by furnace design. On a horizontal furnace installed in a tight crawlspace, a job that takes 45 minutes on an upflow unit in an open basement can take 2 to 3 hours. That's not padding—it's real. Get a quote, not an hourly rate, for this one.

Control Board Replacement: Expensive Diagnosis Required

The control board—sometimes called the circuit board or integrated furnace control—is the brain of the furnace. It sequences the inducer motor, the igniter, the gas valve, and the blower in a precise order, and it reads input from sensors throughout the system. When a board fails, the symptoms can look like almost anything: random lockouts, no response to the thermostat, error codes that don't match any obvious cause.

Boards are expensive. The part alone typically runs $100 to $400 depending on the furnace brand; OEM Carrier or Lennox boards sit toward the top of that range, while aftermarket-compatible boards can be had for less but sometimes introduce their own compatibility issues. Installed, a control board replacement costs $200 to $600 in most markets.

The honest challenge with control boards is diagnosis. A board can fail in ways that mimic other problems—a faulty board might make it look like the pressure switch is bad or the gas valve is dead. Replacing the wrong part first is common and expensive. This is where you want a technician with actual experience on your furnace brand, not someone reading a generic flowchart.

One specific trap: on Goodman and Amana furnaces manufactured before 2018, a shorted control board was a known issue that could recur if the root cause—usually a failed secondary limit switch creating voltage spikes—wasn't also addressed. Replacing the board without fixing the underlying cause means the new board fails within a season. If someone quotes a Goodman board replacement, ask whether they've checked all the limit switches too.

Some technicians will quote a board replacement over the phone based on symptoms alone. That's a guess, not a diagnosis. The board should be confirmed bad with a meter before anyone orders a part.

Heat Exchanger: The High-Stakes Repair

A cracked heat exchanger is the most serious and most expensive furnace problem. The heat exchanger is the metal chamber where combustion gases are contained—it's what keeps carbon monoxide out of your living space. Cracks can allow flue gases to enter the airstream, which is a genuine safety hazard, not a theoretical one. People have been killed by cracked heat exchangers that were missed or ignored.

Replacement costs for a heat exchanger run $500 to $1,500. On many older furnaces, especially those more than 15 to 20 years old, the heat exchanger costs more than the furnace's remaining useful value, which is why replacement rather than repair is almost always the recommendation at this point.

There is a real and documented controversy in the HVAC industry about heat exchanger diagnosis. Some technicians—particularly those who also sell replacement furnaces—have been caught condemning heat exchangers with hairline cracks so small they pose no measurable risk, using this as a reason to push a full system replacement. This isn't universal, but it happens often enough that a second opinion on a heat exchanger condemnation is genuinely warranted.

If a technician tells you your heat exchanger is cracked, ask to see the crack. A responsible tech can show you with a flashlight and a camera probe. If they refuse or can't produce the visual evidence, get a second opinion from an independent technician—not from another salesperson at the same company. The American Gas Association and most state utility commissions support your right to a second opinion before replacement.

On a furnace under 10 years old with a factory warranty still in force, check the warranty terms first. Most manufacturers cover the heat exchanger for 20 years or the life of the furnace. Carrier, Lennox, Trane, and Rheem all have lifetime heat exchanger warranties on certain product lines. This repair may cost you nothing if the paperwork is in order.

Gas Valve, Flame Sensor, and Pressure Switch: The Middle-Tier Repairs

These three components fail regularly and fall in a cost range below a control board but above a capacitor. Understanding what each does helps you evaluate whether the quoted work makes sense.

Flame sensor: A thin metal rod that confirms the burner is actually lit. When it's coated with oxidation, it can't read the flame and the furnace shuts down as a safety precaution. The fix is often just cleaning the rod with fine steel wool—a 10-minute job that costs essentially nothing but a service call. If a flame sensor is genuinely failed (not just dirty), the part costs $5 to $15, and total repair cost should be $75 to $150. Anyone quoting significantly more for a flame sensor replacement is overcharging.

Pressure switch: A diaphragm switch that confirms the inducer motor is creating proper draft before allowing the furnace to fire. Failed pressure switches are common, especially on condensing furnaces where the rubber hoses connecting the switch can crack or clog with condensate. The part runs $20 to $75 depending on whether it's OEM or aftermarket; installed cost is typically $100 to $250. Before replacing the switch itself, a tech should check whether the hose is simply clogged—a $0 fix.

Gas valve: The valve controls gas flow to the burners. A failed gas valve is a serious component failure, and the part is expensive: $100 to $250 for most residential valves, with installed costs of $200 to $500. One important note: gas valves are almost never the actual cause of a no-heat call, even when symptoms point that way. They're durable and fail rarely. A tech who immediately quotes a gas valve without ruling out the igniter, flame sensor, control board, and pressure switch first is working backward through the diagnostic sequence. Push back and ask what was tested before that conclusion was reached.

Inducer motor failure is also worth mentioning here. The inducer (draft) motor runs before ignition to clear the combustion chamber. When it fails, the furnace won't start at all. Inducer motors cost $150 to $350 as parts, and total repair typically runs $300 to $600—similar territory to a blower motor job.

When Repair Stops Making Sense: The Real Math

There's a rule of thumb in the HVAC industry called the 50 percent rule: if a repair costs more than 50 percent of the replacement cost of the system, replace it. It's a reasonable starting point, but it ignores furnace age, which matters more than the repair cost alone.

A better framework uses both variables. Multiply the repair cost by the age of the furnace in years. If the result exceeds $5,000, replacement is usually the smarter financial move. So a $400 repair on a 10-year-old furnace ($4,000) probably makes sense; a $400 repair on a 14-year-old furnace ($5,600) is borderline, especially if the furnace is already showing signs of other wear.

New gas furnaces range from roughly $2,500 to $5,500 installed for a standard 80% AFUE unit, and $3,500 to $7,000 for a high-efficiency 96–98% AFUE model. These are full installed costs including the furnace, labor, new flue pipe, and basic electrical work—not just the equipment price you see advertised. The difference in annual operating cost between an old 80% furnace and a new 96% model depends on your gas price and usage, but a rough estimate for a typical Midwest home is $150 to $300 per year in savings.

The repairs that most strongly argue for replacement instead of fixing are heat exchanger failure (especially on any furnace over 15 years old), a second control board failure on the same unit within a few years, and repeated blower motor issues on a furnace already showing rust and cracks in the cabinet. Any one of these on a furnace approaching 20 years of age is a strong signal.

On the other side: a 6-year-old furnace with a failed igniter or a bad pressure switch is an easy call. Fix it. The repair is cheap, and the furnace has a decade or more of useful life ahead of it. Don't let a repair call become a replacement sale if the numbers don't support it.