7 Expert Solutions for a Furnace That Is Blowing Cold Air

That’s weird. Your heating system is on, but your furnace is blowing cold air. Terrible news, on a freezing winter day in Ontario!

The good news is that your furnace issue can be resolved with help. Consider these seven solutions for a furnace that blows cold air.

Incorrect Thermostat Setting

You believed you had the thermostat set at a cozy level. However, there are occasions when you are comfortable and sense a distinctly cool breeze coming from the vents. Double-check the thermostat. It may be set to ON, meaning the fan will run all the time, even when the furnace is cycling off.

SOLUTION: Change the setting to AUTO.

Other Thermostat Issues

Other issues with your thermostat could be the cause.

1) Battery life may have depleted if it runs on batteries or

2) If you just installed a new thermostat, you might have purchased a type that doesn’t work with your system.

SOLUTION: 1) Replace the battery. OR 2) Consult an HVAC professional to see whether the new thermostat is incompatible with your heating system.

Dirty Air Filter

Is your furnace frequently shutting on and off? Your air filter may be clogged. A gas furnace's safety switch will eventually turn off the burners if the airflow is impeded due to a clogged air filter. Your fan will blow cold air since no hot air is generated.

SOLUTION: Change the filter, if it’s the disposable kind. Or, clean a permanent filter.

Clogged Condensate Line

As a byproduct of their function, high-efficiency furnaces produce condensed liquid. This condensate usually drains harmlessly away. The condensate drain line occasionally clogs up, resulting in a furnace blowing cold air and leaking water.

SOLUTION: Contact a heating and cooling technician to clean the condensate line.

Pilot Light Is Out

Your pilot light may be out for one of two reasons. Either it has simply burned out, or it was never correctly lit. The latter problem may be due to blockage from dirt and soot or a malfunctioning thermocouple.

SOLUTION: Perhaps you should attempt to relight the pilot light by yourself… very carefully. Call an HVAC expert if it won't light or goes out within a minute.

Insufficient Gas Supply

For a gas furnace to operate properly, there must be a sufficient supply of natural gas. Was your gas supply turned off for any reason? Is your gas valve closed? If the answer to both questions is no, a blocked line could interfere with the gas flow.

SOLUTION: Find a furnace repair expert to inspect and fix the gas line.

Leaky Ducts

Older ductwork tends to develop cracks and leaks due to wear and tear. Even though the system is blowing warm air, heat leaks before it ever reaches you, so you feel as if your furnace is blowing cold air.

SOLUTION: Have a professional conduct duct sealing for you.

Our ElectroDust™ Washable Air Filter

ElectroDust filters provide higher than industry average air quality and are built to higher standards. Our environmentally friendly filters allow you to wash and re-use them over a ten-year lifespan. After just ten months of using our filters, you will begin to realize savings. Furthermore, because ElectroDust filters are more efficient at capturing dust and foreign particles, you won’t require duct cleaning as often, saving you even more money. Less dusting means a healthier home.