Why Is My Furnace Blowing Cold Air?

There is a certain panic that comes with the blowing of cold air out of your furnace, which should pointedly be blowing out something warm. Thankfully, this doesn’t mean your furnace is going out and that you’ll require a new one before you can get your home back up to a comfortable temperature. Before any panicking, there are a few things you can look at to try and fix the problem on your own.

Firstly, is the thermostat set correctly?

It is the first, easiest, and sometimes the most overlooked solution for why your furnace is blowing cold air. Take a moment to look at your thermostat, make sure it’s set to a warm degree, that the heat function is turned on, and that it appears to be running correctly. If it’s a new thermostat that you may have applied yourself, it’s possible the one you’ve chosen is not compatible with your heating element. This is something you’ll need to call a professional for, as they may have to go back over work to untangle some of the problems for you. If it isn’t a new thermostat, see if it has batteries. It may simply need a new set. If you believe it is the heater itself, lets move on.

furnace blowing cold air
heating systems should have routine maintenance every fall

Oil tank?

If you have an oil tank heater, it may require more oil. In a less scientific answer, the oil and flames create the warm hair that is pushed through the vents in your home. So when this is gone or too low, the air circulates but hasn’t been warmed at all, which may be why your furnace is blowing cold air. Oil furnaces also have an oil filter. It may need to be changed, and if that is the case, you’ll probably want to call a professional.

Electronic Control System.

If you have a newer furnace with a digital control, it’s possible that the system just needs rebooted. Find the power switch on it and turn it off—wait a moment—then turn it back on again. If that doesn’t help, you may have to call a professional.

Air filter.

If you haven’t changed the air filter in a long time, your furnace could be overheating. If it gets too hot, it will shut off the burner, and thusly, we once again have an issue of air circulating but not heating. Check the filter, and if it’s looking poorly, make sure to read the filter size and replace it. Filters should normally be replaced a couple times a year, but it can easily be forgotten, and this may be a simple fix.

Pilot light.

Older furnaces have a pilot light, a small blue flame, that you can normally see via a tiny window. The pilot light ignites natural gas that is pushed into the furnace’s main burner. If the flame is gone, you can press and hold the reset button while holding a lit match or lighter to the pilot light opening. Once it’s lit, release the button. Give it a minute or two and see if that has helped. If you are not comfortable relighting your own pilot light, there is nothing wrong with asking a professional to come out to help.

What if the Pilot Light won’t light? You’ll need to call a professional. This could be due to an issue with the gas running, in which case it may need to be cleaned or a new valve. This is something you want a professional to do to make sure the gas is being handled correctly from start to finish.

furnace blowing cold air

Hopefully your heater issue is something small and simple. If not, calling a professional about why your furnace is blowing cold air may be the only help for you. Also, furnaces should have routine maintenance and checks, preferably once a year. These small check-ins for your furnace can keep little surprises like this from popping up, or at least make you more aware of things that may start to be going wrong for you to make informed decisions about the heating of your home. Schedule a maintenance check or call for service help with Gnoth and Lukowski Heating and Air Conditioning to keep the temperature of your home stable year-round.

Call the Professionals

HVAC systems are complex so you should leave checkups and repairs to the professionals. Even with a new system, it is important to have biannual services done to make sure your system is running properly. If there is an issue, the technician will be able to identify and correct it before it causes a system failure, costing you thousands of dollars to replace. Regular maintenance will also save you money on your monthly energy bill by keeping your system running at peak performance. 

If you would like to schedule repairs for your HVAC system, visit callgnoth.com/furnace-repair or call Gnoth & Lukowski Heating & Air Conditioning LLC at (574) 287-3550. We have been serving the South Bend-Mishawaka area for over 30 years and offer 24-hour emergency repair services at no extra charge.