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Ambient Comfort LLC Blog

Why Is My Furnace Blowing Cold Air?

Obviously, a furnace blowing cold air is just not a good sign. There are several common causes for such an unlucky scenario, some of which are easily resolved by homeowners, while others require the attention of a heating professional.


The simplest cause is an incorrect thermostat setting. Make sure the function switch is set to the Auto or Heat position. Other thermostat issues to consider are batteries in need of replacement and the possibility that your thermostat may not be compatible with the home’s heating system.

Empty Tank

This is another simple and easily resolved problem. Order some fuel and you’ll be warm in no time.

Pilot and Valve Troubles

Sometimes a stray gust of air might extinguish the pilot light. If you can relight it but it continues to go out, the problem could be a faulty thermocouple. If you can’t relight it at all, a dirty or faulty gas valve might be the culprit.


If your air filter has not been replaced or cleaned recently, it can be result in compromised air flow which can cause a furnace to overheat and shut down the burner. This can be easily resolved by replacing the air filter and restarting the furnace.

Oil Filter

Filters on oil-fired furnaces may become clogged with dirt. With nothing to burn, the furnace blows cold air. The oil filter is not as easy to clean or replace as air filters and is best handled by professional heating system technicians.


Faulty Electronic Ignition


Newer furnaces with electronic ignitions, such as intermittent pilots or hot surface ignitions, may need adjustments or replacement of failed parts.


Compromised Flame Sensor


If a furnace is blowing warm then quickly turns cold, the flame sensor could be the cause. A dirty flame sensor can cause the burner to shut off.


Dirty Oil or Gas Burner


If a burner has been neglected and hasn’t received a cleaning in a long time, grime can build up, and this can cause ignition troubles.


Leaking Ducts


Hot air can escape through rust holes in duct work or between duct sections that have become separated. Repairs to ducts are another job for the pros.


Most furnace problems can be prevented with regularly scheduled cleaning and maintenance from a professional heating company. Schedule your HVAC winter service now to ensure your heating system is in optimal working order and prevent unexpected failures.


When it comes keeping your home warm in winter with an efficient heating system, the professionals at Ambient Comfort provide the service and equipment you need. Call us in Vineland today at 856-213-6586 for professional heating service throughout South Jersey, in the counties of Atlantic, Burlington, Camden and Gloucester. We are here to serve you!

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