Surviving the Cold Front: Why Your Furnace Blows Cold Air

Young woman shivering on the sofa

Cool air from the vents is a blessing in August. Not so much in January.

It will have you scratching your head in confusion, muttering in frustration, turning the garage inside out for the space heater you haphazardly stored last spring, and ultimately rushing to the store for a new space heater to warm just a tiny portion of your frigid home.

Do you have a serious problem on your hands? Maybe, and maybe not. We’ll offer the weasley answer of “it depends,” and review some of the reasons why your furnace might be blowing cold air. Rejoice — there could be a DIY fix!

10 Reasons Why Your Furnace Is Blowing Cold Air

  1. Thermostat Settings: You’d be surprised how often this is the culprit. If your thermostat is on the ‘fan only’ setting, it will push out cold air when the heating cycle isn’t running. No need to fret! Simply adjust the thermostat to ‘auto’ mode. Voila! It’s a DIY fix.
  2. Dirty Air Filter: A clogged air filter can block airflow and cause the heat exchanger to overheat and shut off too quickly. Your furnace won’t have enough time to warm the air before shutdown. Cleaning or replacing your air filter might do the trick — another DIY solution.
  3. Pilot Light Problems: If your gas furnace’s pilot light is out, it won’t be able to heat air. This is a tad more serious, but you may be able to reignite the pilot light yourself. However, if it keeps going out or doesn’t light at all, call a professional for help.
  4. Fuel Supply Issues: Your gas furnace won’t produce heat if there’s an issue with the gas supply. Check to see if the gas valve is fully open and the supply is uninterrupted (and that you paid your bill!). If the problem persists, call a professional.
  5. Faulty Components: A malfunctioning ignition system or a broken blower motor could cause the system to blow cold air. These issues can be tricky to diagnose and even trickier to repair. Leave the job to the pros.
  6. Ductwork Issues: Leaks or blockages in your ducts can prevent warm air from reaching all areas of your home, leaving some rooms colder than others. A professional duct cleaning and sealing can solve this issue.
  7. Dirty Heat Exchanger: Dirt or corrosion reduces a heat exchanger’s efficiency. Regular maintenance can help prevent this issue, but your furnace may need a professional cleaning if the dirt is encrusted or corrosion has already occurred.
  8. Wrong Furnace Size: If your furnace is too big or too small for your home, it may struggle to heat your space and blow cold air instead of warm air. It’s best to consult an HVAC professional to determine the correct furnace size for your home.
  9. Insufficient Insulation: If your home is poorly insulated, warm air could be escaping before it even gets a chance to circulate. This might leave you feeling like your furnace is blowing cold air. If certain rooms are warmer than others, or if your heating bills are unusually high, you might consider having your insulation checked and possibly upgraded.
  10. Lack of Maintenance: Your furnace needs regular maintenance to keep it working correctly. Parts can wear out or get dirty without regular tune-ups, which might lead to your furnace blowing cold air. Scheduling routine maintenance with a professional can prevent these problems and keep your home cozy.

Signs Your Furnace Needs Attention

Here are some telltale indications of furnace trouble:

  1. Unusual Noises: If your furnace starts making weird sounds — think bangs, whines, or scrapes that weren’t there before — that’s a clue something’s off. Furnaces should operate quietly, so check out any new or intensifying noise.
  2. Inconsistent Heating: Are some rooms in your home toasty while others feel like the Arctic? Your furnace might strain to distribute heat evenly, pointing to potential ductwork issues or a failing motor.
  3. Rapid Cycling: If your furnace turns on and off several times an hour, or ‘cycling,’ more frequently than usual, this could indicate a problem — potentially a bad thermostat, improper airflow, or overheating.
  4. Increased Heating Bills: A sudden spike in your heating bills without a corresponding increase in usage is a clear warning signal. It suggests your furnace works harder than necessary, indicating an efficiency problem.
  5. Yellow Pilot Light: The pilot light on your gas furnace should be a clear, blue flame. If it’s yellow or a different color, it could point to improper combustion, a serious issue requiring immediate attention.

Furnace Maintenance & Repair in Los Angeles

Do you live in metro Los Angeles and need a furnace inspection or repair? Or a new installation?

Call West Coast Chief for guaranteed furnace service and same-day service visits.

Chief employs only certified technicians and guarantees all repairs. We service all brands, honor manufacturer warranties, and use only certified parts in any repair we perform.

Don’t wait until your furnace becomes a problem or liability. Call us today! 888-832-3599.

Contact Us for Service

FAQs about Furnaces & Cold Air

Q: Is cold air always a serious issue?

A: Not necessarily. Sometimes, simple troubleshooting can resolve the problem. However, consistent cold air blowing from your furnace could indicate an underlying mechanical issue that requires attention.

Q: Is a faulty thermostat easy to fix?

A: Some thermostat problems can be fixed by recalibration or replacement. Consult a professional for accurate diagnosis and resolution.

Q: What can make the pilot light go out?

A: Several factors can cause a pilot light to go out, such as drafts, dirt buildup, or a malfunctioning thermocouple. It’s best to have a professional assess the situation if your pilot light keeps going out.

Q: How often should I change my furnace filter?

A: We recommend that you change your furnace filter every 90 days. However, if you have pets or someone in your home has allergies, you may want to change it more frequently.

Q: Can a dirty air filter make a furnace stop working?

A: Accumulated dirt and dust can block airflow, causing the furnace to overheat and shut down.

Q: How can I tell if my furnace is too big or too small for my home?

A: If your furnace frequently turns on and off, it might be too big for your home. Conversely, if it seems to run constantly and struggles to reach a comfortable temperature, it might be too small.

Q: What is the average lifespan of a furnace?

A: Most furnaces last between 15 to 20 years with regular maintenance. However, the lifespan can vary based on the quality of the unit and how well it’s maintained.

Q: Is there any harm in postponing furnace maintenance?

A: Yes, delaying furnace maintenance can lead to decreased efficiency, higher energy bills, and even safety risks. Regular maintenance helps keep your furnace running optimally and can extend its lifespan.

Q: How often should I schedule furnace maintenance?

A: We recommend maintaining your furnace at least once a year, ideally before the heating season begins.

Q: What are the benefits of upgrading to a more efficient furnace?

A: Upgrading to a higher-efficiency furnace can result in lower energy bills, better temperature control, and improved indoor air quality — all with a smaller carbon footprint.


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