Furnace Not Igniting in Oak Lawn? Fast Repair Service
When your furnace won't light or keeps trying to ignite without success, you need fast, reliable repair—especially during Oak Lawn's cold winters. Clucas Mechanical diagnoses and fixes furnace ignition problems same-day in most cases.
Common Causes of Furnace Ignition Failure
1. Failed Hot Surface Igniter
Modern furnaces use a hot surface igniter (looks like a small glowing element) to light the gas. These igniters are fragile and typically last 3-7 years. When they fail, you'll hear the furnace start, the inducer motor run, but no ignition occurs.
Symptoms: Inducer motor runs, no flame, furnace shuts down after 3-4 attempts
Repair: Replace igniter ($180-$380 installed). We carry common igniters and can complete repairs same-visit.
2. Dirty or Faulty Flame Sensor
The flame sensor is a small metal rod that confirms the burners are lit. If it's covered in carbon buildup or has failed, it tells the furnace to shut off gas even when burners ignite. You'll see flames for 2-5 seconds, then the furnace shuts down.
Symptoms: Burners light briefly then shut off; repeats every few minutes
Repair: Clean flame sensor with emery cloth or replace if faulty ($150-$350).
3. Pressure Switch Problems
High-efficiency furnaces have a pressure switch that confirms the inducer motor is creating proper draft before allowing ignition. A stuck switch, disconnected hose, or clogged port prevents ignition.
Symptoms: Inducer motor runs, then furnace shuts down without attempting ignition
Repair: Clear obstructions, replace switch if failed ($220-$550).
4. Clogged Condensate Drain (High-Efficiency Furnaces)
Many Oak Lawn homes have 90%+ AFUE furnaces that produce condensate. If the drain is clogged, a safety switch prevents ignition to avoid water damage and backdrafting.
Symptoms: Furnace won't start at all, or starts then shuts down; may have water near furnace
Repair: Clear condensate drain, clean trap, verify proper slope ($150-$400).
5. Gas Valve or Supply Issues
If the gas valve has failed or gas supply is interrupted, the igniter will glow but no flame appears. This is less common but critical to diagnose correctly.
Symptoms: Igniter glows orange/white, no gas ignites, smell no gas odor
Repair: Test gas pressure, check valve operation, replace valve if failed ($480-$1,200).
6. Limit Switch or Rollout Switch Tripped
If your furnace overheated (often due to restricted airflow) or had a rollout event, safety switches may prevent re-ignition until reset or replaced.
Symptoms: Furnace completely unresponsive or blower runs but no heat attempt
Repair: Identify root cause (dirty filter, blocked vents), reset or replace switch, correct airflow issue ($150-$600).
Why Oak Lawn Furnaces Face Unique Challenges
Oak Lawn's housing stock includes many mid-century homes with aging HVAC infrastructure:
- Older ductwork with restrictive returns: Causes overheating and limit switch trips, preventing ignition
- Finished basements with furnaces: Often have undersized filter racks that choke airflow
- High-efficiency retrofits in older homes: Condensate drainage issues if not properly sloped
- Venting through old chimneys: Can cause backdrafting and pressure switch issues in cold weather
We assess these factors during diagnosis to prevent repeat failures.
Our Furnace Repair Process
- Emergency Response: Priority scheduling for no-heat calls, especially when temperatures drop below 20°F
- Safety-First Diagnosis: Carbon monoxide testing, gas leak checks, and combustion analysis
- Complete System Evaluation: We don't just fix the symptom—we find the root cause
- Transparent Pricing: Written estimate before repair, with repair vs. replace guidance for older systems
- Quality Parts: OEM or better replacement parts with manufacturer warranty
- Post-Repair Testing: Verify proper ignition sequence, flame pattern, temperature rise, and safety controls
Furnace Repair Costs in Oak Lawn
- Diagnostic visit: $89-$149
- Igniter replacement: $180-$380
- Flame sensor cleaning/replacement: $150-$350
- Pressure switch replacement: $220-$550
- Condensate drain cleaning: $150-$400
- Inducer motor replacement: $450-$850
- Gas valve replacement: $480-$1,200
- Control board replacement: $480-$1,200
What You Can Check Before Calling
- Check your thermostat: Set to HEAT, temperature above current room temp, batteries fresh
- Replace your furnace filter: A severely clogged filter can trigger safety shutdowns
- Check circuit breakers: Furnace breaker at panel and furnace switch near unit should both be ON
- High-efficiency furnaces only: Check PVC vent pipes outside—clear ice, snow, or obstructions
- Listen for sounds: Note what you hear (clicking, humming, whooshing) to help our technician diagnose
Safety warning: If you smell gas (sulfur/rotten egg odor), don't attempt repairs. Leave immediately, call your gas company from outside, then call us once safe.
When to Consider Furnace Replacement
If your furnace is 15+ years old and requires one of these repairs, replacement may be smarter:
- Heat exchanger failure (immediate safety risk)
- Cracked heat exchanger (carbon monoxide risk)
- Multiple component failures within 1-2 years
- Repair costs exceeding $1,000 on a 15+ year furnace
New high-efficiency furnaces (95%+ AFUE) can cut heating costs by 25-35% compared to older 80% units, often paying for themselves in 7-10 years through energy savings.
Frequently Asked Questions
- Why won't my furnace ignite in Oak Lawn?
Common causes include failed igniter, dirty flame sensor, gas supply issues, pressure switch faults, or clogged condensate drain on high-efficiency furnaces. Our technicians diagnose and fix these same-day in most cases. - Is it dangerous if my furnace won't start?
Usually not immediately dangerous, but never ignore gas smells. If you smell gas, leave immediately and call your gas company. For other ignition failures, turn off the furnace and call for service. - How much does furnace ignition repair cost?
Igniter replacement: $180-$380. Flame sensor cleaning: $150-$250. Pressure switch or inducer motor: $220-$650. Gas valve replacement: $480-$1,200. We provide exact pricing after diagnosis. - Can I replace the igniter myself?
While possible for handy homeowners, we don't recommend it. Improper installation can cause gas safety issues, carbon monoxide risks, or further damage. Professional installation ensures safety and warranty coverage. - How long does furnace repair take?
Most ignition repairs take 1-2 hours when we have the part on our truck. Special-order components may require a follow-up visit, but we can often source parts same-day from Chicago-area suppliers.
Get Your Furnace Running Today
Don't wait until temperatures drop further. Call Clucas Mechanical at (708) 674-3600 for fast furnace ignition repair in Oak Lawn. We prioritize no-heat emergencies.