It’s the first truly cold night of autumn and time to turn up the heat. You were hoping for no surprises, but no such luck! Now, you find yourself wondering, “Why is my furnace blowing cold air?”

Dropping Temps

Temperatures on the Atlantic seaboard can really drop in November, with average low temperatures in December and January easily hitting the 20s. It’s no time for your heating system to fail.

Diagnosing a Failed Furnace

If your home has no other source of heat, don’t wait too long before calling an HVAC technician. However, you can try to it yourself using the following checklist to ensure you haven’t missed something.

Sudden blast of cold air

If your furnace blows out cold air initially that soon becomes warm, you don’t have a problem. Your air handler fan will start immediately, before there is warm air to move. If the air stays warm, you have nothing to worry about.

Thermostat

It seems obvious, but have you checked the thermostat? Someone else in your household may have turned it off.

You may have not set it properly. If you turned the setting to “ON,” you have just turned on the fan. Make sure the thermostat is on “AUTO” and the temperature setting is correct to engage the heat.

Another thermostat issue may be something as simple as a dead battery

Pilot light problems

If you have a gas furnace, your next step is to check the pilot light. If it has gone out, check your manufacturer's instructions for relighting the pilot light.

If you are unable to light the pilot light, then go to the next step.

No Fuel

If your natural gas furnace isn’t getting fuel, you’ll get cold air as long as the line is restricted. You’ll need to call an HVAC technician to fix the problem.

For oil or propane furnaces with holding tanks, you may simply need to order fuel.

Furnace overheat

If there doesn’t seem to be a lack of fuel, then examine your air filter. A dirty air filter causes your furnace to overheat or short-cycle. Then, the limit switch will shut down the burners, and the fan will continue to push out cold air.

Allow the unit to cool while changing the air filter, then try again.

Dirty components

It could also be the flame sensor on your gas furnace. Pilotless ignition furnaces utilize a flame sensor. These sensors can become dirty or damaged. The gas and oil burners themselves can also become dirty, and the accumulation of grime will make it difficult for them to stay lit.

Time to Call a Pro

If you’ve eliminated any causes that you can fix yourself, and it’s still blowing cold air, it’s time to call in a pro.

Make an appointment today with the experts at One Hour Heating & Air Conditioning in Pleasantville. We also offer Emergency HVAC services to ensure you stay safe and warm all winter long.