Why Is My Furnace Blowing Cold Air?

At 72 Degrees Air Conditioning & Heating, one of the most common furnace issues our customers experience is when their furnace is blowing cold air. On some occasions, it’s a simple fix that the average homeowner can do on their own, while other times the problem requires professional work. The following checklist may help you identify the issue.

Inspect the Filter

Clogged filters do not only result in an inefficient furnace, but they can lead to the system overheating. Filthy filters obstruct airflow, resulting in your furnace taking much longer to heat your home than it should.

If this is the source of the issue, your heating system will blast warm air, then suddenly cold air, and eventually cease to blow air altogether. Most furnace models are equipped with a build-in safety feature which shuts the burners off when the furnace becomes overheated, but the blower will remain on to cool the furnace at a safe temperature. So if you notice that your filter is dirty, please replace it.

Check the Thermostat

There are a variety of issues that stem from the thermostat, such as:

  1. The thermostat is set lower than the home’s temperature
  2. The thermostat is set to ON instead of AUTO
  3. Dead or dying batteries in the thermostat

For example, when the thermostat is set to ON, the fan will continue to run despite the furnace not heating the air. However, switching the fan setting to AUTO will allow the furnace to blow warm air throughout your home.

Check the Pilot Light

A gas furnace is equipped with a pilot light, which is a small flame that is continuously burning to help the system ignite more effortlessly. If the pilot light is out, then it may be the cause of the cold air.

Try to relight the pilot light. If it doesn't light or stay lit, however, there could be components that require cleaning or even replacement. Pilot lights are considered a fire hazard if they are not in working order, so please contact licensed contractor to take a closer look at the problem.

Examine the Fuel Source

Whether your furnace runs on gas, oil, or electricity, ensure that your unit is receiving its proper fuel supply. Electric systems must be turned on at the breaker level and at the unit’s ON/OFF switch, gas valves need to remain open to allow the fuel to use by the burners, and oil tanks must have an adequate amount of oil in order for the unit to run efficiently.

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If your furnace requires immediate repairs and you live in Fredericksburg, TX, contact 72 Degrees Air Conditioning & Heating and schedule an appointment with our licensed technician today.