Every time your thermostat calls for heat, the furnace runs a fixed checklist. The inducer motor starts and proves draft by closing a pressure switch, the hot surface igniter heats up, the gas valve opens, the burners light, and the flame sensor confirms there is fire. Only after all of that does the blower begin sending warm air into the house. Finding the step that fails is most of the job. Around Dunwoody, GA, the usual failure points are a flame sensor fouled with oxide, an igniter cracked by years of heating and cooling, a pressure switch that stays open because of a weak inducer or a clogged condensate trap on a high-efficiency unit, and control boards with burned relays. Any one of them halts the startup, and from the hallway they all look alike.
Our experienced technicians diagnose a furnace the way it operates, in order, measuring each stage as it happens. That means igniter resistance, microamp flame signal, pressure switch operation under actual inducer draft, gas valve voltage, and blower and capacitor condition. Safety checks are never optional on a gas appliance: heat exchanger inspection, leak testing on the gas connections, and flue draft verification, since a hazard is not visible at the thermostat. We finish by checking temperature rise against the data plate, making sure the burner and blower work together the way the manufacturer designed them to.
Dunwoody HVAC services natural gas, propane, and electric furnaces from all major brands, from standard 80 percent units to condensing high-efficiency models with their traps, drain lines, and dual pressure switches. Our trucks carry the parts that really fail, such as igniters, flame sensors, pressure switches, capacitors, inducer assemblies, and blower motors, so a typical no-heat call ends with the house warming up. Call (470) 200-3365 for furnace repair anywhere in Dunwoody, and we can have someone out today.
For air conditioning breakdowns, see AC Repair in Dunwoody.
How Much Does Furnace Repair Cost in Dunwoody?
Most furnace repairs in Dunwoody cost between $150 and $600. The price depends on which part failed and how old the furnace is. You'll get a written, upfront price from Dunwoody HVAC after we diagnose the problem.
| Repair | Typical cost | What it usually means |
|---|---|---|
| Flame sensor cleaning or replacementBurners light but cut out almost immediately | $80–$250 | Burners light but cut out almost immediately |
| Hot surface igniter replacementFurnace clicks and tries to start but never lights | $150–$400 | Furnace clicks and tries to start but never lights |
| Draft inducer motorLoud humming or grinding at startup, then lockout | $400–$1,000 | Startup fan fails, furnace won't fire |
| Blower motorBurners run but little or no air comes out of the vents | $400–$1,500 | Burners run but little or no air comes out of the vents |
| Control boardFurnace won't respond to the thermostat | $300–$700 | Erratic behavior, error codes, or no response at all |
| Gas valve replacementValve fails to open, so the furnace never lights | $250–$700 | Igniter glows but gas never flows to the burners |
Ranges are typical for these repairs; you get an exact quote before any work starts.
Factors That Change the Price
- Furnace age and type, because 90%+ efficiency models have more specialized parts
- A cracked heat exchanger, which is a safety issue and usually points to replacement
- Same-day or after-hours service versus a planned visit
- Access to the furnace in attics, closets, or crawlspaces
For older furnaces facing a big repair, we'll show you what replacement would cost too, so you can compare. No heat right now? Call (470) 200-3365.
Warning Signs for Furnace Repair
The sooner you notice these red flags, the easier and cheaper the problem is to resolve. Here are the most common indicators that it's time to call a professional:
- A bang or boom when the burners ignite late
- A furnace that shuts off every few minutes before the house warms up
- Repeated shutdowns just seconds after the burners light
- A pilot or burner flame that is lazy yellow instead of crisp blue
- Water, rust stains, or black soot around the flue or cabinet
- Clicking and a glowing igniter with no burner flame
- A fan that keeps running while the registers blow cool air
- Squeals, scrapes, or grinding noises behind the blower door
Early Action Saves Money
Most HVAC failures start small, a weak capacitor, a squealing blower, a system that runs a little longer each week. Don't wait, get Dunwoody HVAC on the phone at (470) 200-3365 and we'll take a look right away.
Furnace Repair Issues? We Can Help.
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Why Hire a Professional for Furnace Repair?
The most serious furnace problem is usually hidden. A cracked or corroded heat exchanger can let combustion gases into the airstream, and nothing about it is visible from the outside of the cabinet. Delayed ignition makes things worse, because each boom at light-off puts more stress on that metal. Add high voltage, a gas valve, and a flue to the same box, and there is little room for guesswork. Diagnosis is full of traps too. A high limit that keeps tripping could be a bad switch, or it could be doing exactly its job because a filter is clogged or the blower is dying, and swapping out a working switch only hides the real fault.
Our experienced technicians look at every symptom in the context of the whole furnace. We measure flame signal instead of assuming it, which keeps us from replacing a healthy sensor while a cracked igniter or weak gas valve goes unnoticed. Draft is confirmed at the pressure switch and at the flue. Temperature rise is checked against the data plate, catching airflow problems before they cut years off the heat exchanger. The gas side is leak-tested with instruments, never with a quick sniff. The result is a furnace proven safe over a full cycle, plus an honest opinion if the unit is getting close to the point where replacing it beats repairing it again.
Our Furnace Repair Process
Our systematic workflow delivers thorough, lasting results on every job. Here's what you can expect when you choose Dunwoody HVAC:
Sequence Diagnosis
Instead of guessing, we follow the startup sequence one stage at a time, with readings on the inducer, pressure switch, igniter, flame sensor, and gas valve, until the broken link shows itself.
Safety Inspection
The heat exchanger is inspected, gas connections are leak-tested, and flue draft verified on every visit. A furnace repair that is not proven safe is not finished.
Expert Repair
The typical repair finishes in one trip. The common failure parts, from igniters and flame sensors to pressure switches, capacitors, and motors, are stocked on the truck and ready to go.
Complete Verification
We finish with a full-cycle test: temperature rise matched to the data plate, smooth ignition with no booming, and every limit switch and safety control confirmed working.
Furnace Repair Prevention Tips
A few simple habits now, like regular filter changes and seasonal tune-ups, can add years to your system's life. Here are our expert recommendations:
- Replace the filter every month while the furnace is working hard, since it costs less than any other part
- Schedule service each fall to catch worn igniters and dirty sensors before cold weather arrives
- Avoid packing the utility room, because burners need open space for combustion air
- Clear boxes, lint, and above all chlorine-based cleaners out of the furnace area
- Notice how the furnace sounds at startup, because a quiet light-off is healthy and a boom is not
- On high-efficiency models, keep the condensate trap and drain line clear and draining
- Put a carbon monoxide detector on every level and test them monthly
Comparing DIY and Professional Furnace Repair
A homeowner can swap a filter with ease, but diagnosing capacitors, refrigerant charge, control boards, and error codes calls for the equipment and know-how only a pro brings. Here's a comparison:
| Factor | DIY Attempt | Professional Service |
|---|---|---|
| Heat Exchanger | Damage hidden inside the cabinet | Checked every time we open the unit |
| Ignition Faults | Guesswork based on blink codes | Igniter, sensor, and valve each metered |
| Gas Connections | Small leaks missed entirely | Instrument leak test on each visit |
| Limit Trips | Limit replaced, cause left behind | The airflow fault behind the trip found |
| Blower Setup | Fan speed never checked | Temperature rise set to the data plate |
| Verification | Declared fixed after one flame | Complete cycles tested before we leave |
Get Furnace Repair Help Today
Don't let a failing system get worse. Call Dunwoody HVAC now for prompt, professional service.
Call (470) 200-3365 TodayWhere We Provide Furnace Repair
We serve Dunwoody and its neighboring communities for furnace repair, from quick same-day repairs to planned installs.