Furnace Not Heating? Expert Diagnosis & Repair
When your furnace runs but doesn't produce heat, or won't turn on at all, it can make your home uncomfortably cold and even dangerous during winter months. Quick diagnosis is essential.
Signs & Symptoms
Possible Causes
- -Thermostat set incorrectly
- -Dirty or clogged air filter
- -Pilot light out (older furnaces)
- -Faulty igniter or flame sensor
- -Gas supply issue
- -Blower motor problems
- -Cracked heat exchanger
- -Dirty burners
- -Tripped safety limit switch
DIY Troubleshooting Steps
Try these steps before calling a professional (unless it's an emergency):
- 1Check thermostat settings (set to "heat")
- 2Replace air filter if dirty
- 3Check pilot light (older systems)
- 4Verify gas valve is open
- 5Check circuit breaker
- 6Make sure vents aren't blocked
- 7Reset furnace by turning off/on
When to Call a Professional
- !Smell gas (leave house, call gas company)
- !Furnace won't stay lit
- !You hear unusual sounds
- !Basic troubleshooting doesn't work
- !Furnace is 15+ years old
- !Yellow or flickering pilot flame
Estimated Repair Costs
Diagnostic: $89-$129
Minor Repair: $150-$400
Major Repair: $500-$2,000
Igniter and flame sensor are minor repairs. Heat exchanger issues may require replacement.
Prevention Tips
Frequently Asked Questions
Why is my furnace blowing cold air?
Common causes include a dirty filter restricting airflow, pilot light issues, a faulty igniter, or overheating causing the limit switch to trip. Check your filter first, then call for professional diagnosis.
Is it dangerous if my furnace isn't heating properly?
It can be. A cracked heat exchanger can leak carbon monoxide. If you smell gas, notice soot around the furnace, or experience headaches/nausea when the furnace runs, evacuate and call for emergency service.
Need Help?
This issue may require emergency service. Call now for immediate assistance.
* 15+ Years Serving the Bay Area
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