Quick Answer
If your furnace isn't heating, start by checking your thermostat (set to HEAT, above room temp, fan on AUTO), air filter (replace if dirty), and circuit breaker (reset if tripped). These three checks fix about 30% of "no heat" calls. If those don't help, you likely have a failed ignitor, dirty flame sensor, or tripped safety switch—all requiring professional diagnosis. In Charlotte, same-day furnace repair is usually available during heating season.
It's 35°F outside and your furnace isn't heating. The thermostat is cranked up, but cold air is still coming from the vents. Before you panic about a huge repair bill or start shopping for space heaters, let's work through this systematically.
Many furnace problems have simple fixes you can do yourself in minutes. In this guide, we'll walk through the DIY checks first, then explain what's happening if you need professional help. After 18 years of fixing Charlotte-area furnaces, we've seen it all—and about one-third of "no heat" calls turn out to be things the homeowner could have fixed.
Quick Fixes You Can Do Right Now (DIY)
Start with these checks before calling anyone. They take 5-10 minutes and resolve about 30% of furnace heating problems.
1. Check Your Thermostat Settings
This sounds basic, but thermostat issues cause a surprising number of service calls. Here's exactly what to verify:
Thermostat Checklist
- Mode is set to HEAT (not Cool or Off)
- Temperature is set ABOVE current room temperature
- Fan is set to AUTO (not ON)—"ON" runs the fan constantly even when the furnace isn't heating
- Batteries are fresh if your thermostat uses them
- No error codes or blinking lights on the display
- Schedule hasn't changed (if programmable)
The "Fan ON" Mistake
2. Check and Replace Your Air Filter
A severely clogged filter is one of the most common causes of furnace problems—and one of the cheapest to fix. Here's why it matters:
- A dirty filter restricts airflow through the furnace
- Restricted airflow causes the furnace to overheat
- When the furnace overheats, the high-limit switch shuts it down (a safety feature)
- The furnace cools, restarts, overheats again, and cycles repeatedly
- Eventually, it may stop trying altogether
How to Check Your Filter
Cost: $5-$30 for a new filter. Time: 2 minutes. A $10 filter change could save you a $150 service call.
3. Check Your Circuit Breaker
Your furnace has its own circuit breaker. If it's tripped, the furnace won't run at all—or only the blower will run (circulating cold air).
How to Reset Your Furnace Breaker
- 1
Find Your Electrical Panel
Usually in the garage, basement, or utility closet.
- 2
Locate the Furnace Breaker
Look for a breaker labeled "Furnace," "HVAC," or "Air Handler." It's typically a 15-20 amp single breaker.
- 3
Check for Tripped Position
A tripped breaker sits in the middle—not fully ON or OFF. It may also have an orange or red indicator.
- 4
Reset Properly
Flip the breaker fully OFF, wait 30 seconds, then flip it back ON.
💡 If it trips again immediately, STOP—you have an electrical problem that needs professional diagnosis. Don't keep resetting it.
4. Check the Furnace Power Switch
Most furnaces have a dedicated power switch nearby that looks like a light switch. It's easy to bump accidentally, especially when accessing storage near the furnace.
Finding the Power Switch
5. Check Your Gas Supply
If your furnace is gas-powered (most in Charlotte are), verify the gas is actually reaching the unit:
Gas Supply Checklist
- Gas valve near furnace is in the ON position (handle parallel to pipe)
- Other gas appliances work (stove, water heater)
- You've paid your gas bill (seriously, this happens)
- No gas smell (if you smell gas, leave immediately and call the gas company)
Need Help With Your HVAC?
$89 diagnostic fee waived with repairs. Same-day service available.
Problems That Need Professional Repair
If the DIY checks didn't solve your problem, you're likely dealing with one of these common furnace issues. These require a licensed technician to diagnose and repair safely.
6. Failed Ignitor (Most Common)
Modern furnaces use electronic ignitors (no pilot light). When the ignitor fails, the furnace can't light the burners. You'll often see the furnace trying to start—the blower comes on, you hear clicking—but no heat.
- Symptoms: Furnace cycles on/off without producing heat, clicking sounds
- Cause: Ignitors wear out with age and repeated heating/cooling cycles
- Repair cost: $200-$400 including parts and labor
- Time to fix: 30-45 minutes
7. Dirty Flame Sensor
The flame sensor is a safety device that detects whether the burners actually lit. If it's dirty, it can't sense the flame and shuts down the gas as a precaution.
- Symptoms: Furnace lights briefly, then shuts off after a few seconds
- Cause: Carbon buildup on the sensor from normal operation
- Repair cost: $100-$250 for cleaning or replacement
- Time to fix: 20-30 minutes
Can I Clean the Flame Sensor Myself?
8. Tripped Safety Switches
Furnaces have multiple safety switches that shut down operation when something's wrong. The two most common:
- High-limit switch: Trips when furnace overheats (often due to restricted airflow from dirty filter)
- Pressure switch: Trips when exhaust venting is blocked or inducer motor fails
These switches exist to prevent fires and carbon monoxide poisoning. When they trip, they're telling you something is wrong—simply resetting them doesn't fix the underlying problem.
Furnace Repair Costs in Charlotte
Common Furnace Repair Costs
| Repair | Cost Range | Time to Fix |
|---|---|---|
| Diagnostic Fee | $89 | 30-60 min |
| Flame Sensor Cleaning | $100-$250 | 20-30 min |
| Ignitor Replacement | $200-$400 | 30-45 min |
| Thermocouple Replacement | $100-$200 | 30 min |
| Pressure Switch | $150-$350 | 45-60 min |
| Draft Inducer Motor | $400-$700 | 1-2 hours |
| Blower Motor | $400-$900 | 1-2 hours |
| Gas Valve | $300-$600 | 1-2 hours |
| Control Board | $400-$800 | 1-2 hours |
| Heat Exchanger | $1,500-$3,000 | 3-5 hours |
Prices include parts and labor. Kodiak's $89 diagnostic is waived with repairs.
Real Customer Review★★★★★"Called Kodiak when our furnace quit on the coldest night of December. They came first thing the next morning—it was just a bad ignitor. $175 and we had heat again. Really appreciated the quick response."
When to Call for Emergency Furnace Service
Most furnace problems can wait until the next business day. However, call for immediate service if:
- You smell gas (leave the house first, then call the gas company and an HVAC tech)
- Your carbon monoxide detector is alarming (evacuate immediately)
- Temperatures are below freezing and you have no alternative heat source
- Vulnerable family members (elderly, infants, those with medical conditions) are at risk
- You see smoke or flames from the furnace
If You Smell Gas
Preventing Future Furnace Problems
Furnace Maintenance Checklist
- 1
Change Your Filter Monthly During Heating Season
A clean filter is the single most important thing you can do. Set a phone reminder.
- 2
Schedule Annual Professional Maintenance
A fall tune-up catches problems before heating season. The technician will clean the flame sensor, check the heat exchanger, and verify safe operation.
💡 Kodiak Care Club ($19.95/mo) includes two annual tune-ups plus 15% off repairs.
- 3
Keep Vents and Returns Clear
Don't block supply vents with furniture or close off too many rooms. Your furnace needs proper airflow.
- 4
Listen for Changes
New sounds—banging, squealing, clicking—often indicate developing problems. Address them before they become failures.
- 5
Know Your Furnace's Age
Furnaces typically last 15-30 years. After 15-20 years, consider replacement before a winter breakdown forces your hand.
Should You Repair or Replace Your Furnace?
Repair vs. Replace Decision Guide
| Feature | Repair Makes Sense | Consider Replacement |
|---|---|---|
| Furnace Age | Under 12-15 years | Over 18-20 years |
| Repair Cost | Under $400 | Over $800 or 50% of new |
| Repair History | First major repair | Multiple repairs recently |
| Heat Exchanger | Not affected | Cracked (safety issue) |
| Energy Bills | Stable | Increasing significantly |
| Comfort | Even heating | Cold spots, uneven temps |
Kodiak HVAC Advice
Frequently Asked Questions
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Written by
Kodiak HVAC Team
HVAC professional at Kodiak Heating & Cooling.