3 Chilly Reasons Why Your Furnace Will Blow Cold Air This Winter

September 23, 2013

During the winter season in the Kansas City area, we live and die by our heating systems.

So if yours starts blowing cold air, it would be easy to panic. 
 
Don’t. Panic. 
 
The causes of this problem are usually easy-to-solve.  Here are 3 reasons why your furnace might blow cold air—and what you can do about them.  

1) Someone messed with your thermostat—probably the cat

Let me ask you, is your furnace only blowing hot air sometimes and cold air other times? Is the furnace’s blower running constantly?

No problem. Your thermostat’s fan setting is set to “ON” instead of “AUTO.” ON means the furnace’s blower runs constantly, even when it’s not heating the air. AUTO means that the blower automatically runs only when the furnace is heating the air.
 
Why it’s set to ON, who can say? But we like to blame the cat (blaming your fish may not be as convincing). 

2) Pilot light is out

If you have an older gas furnace and you’re not getting any hot air at all, the pilot light may be out.

To relight it, follow these steps:
 
Step 1: Locate the pilot light assembly and reset switch
The assembly and switch are usually located at the bottom of the furnace near a small knob that usually these 3 settings: 

  • "Pilot" 
  • "Off"
  • "On"

Can’t find it? Find your furnace user manual and there should be a diagram to show you where it is.
 
Step 2:  Turn the knob to the "off" setting
Turn the knob to the “off” setting and wait 3-5 minutes to make sure no gas coming out of the pilot.
 
Step 3: Light the pilot light
OK, moment of truth. Turn the knob to the "pilot" setting. This re-starts the flow of gas to the pilot. Hold down the reset button on the pilot control panel. Hold your lighter to the pilot opening until the flame lights (the flame should be a steady blue cone). Turn the knob to the “on” setting and the furnace should ignite. 
 
Congrats! Your furnace should be blowing hot air now.
 
If the pilot flame won’t stay lit, the opening may need cleaning or the thermocouple, a safety device, may be malfunctioning and needs replacing.  

3) No supply of gas

Another problem may be the lack of supply of gas to the furnace.

There are a few causes for this:

  • A closed gas valve. Make sure your furnace’s gas valve switch is parallel/in line with the gas supply pipe. That’s the “on” position. 
  • Gas supply company is having problems. Contact your gas supply company to see if they are having any issues supply gas to your home.

So, there you have it: 3 chilly reasons why your furnace might blow cold air this winter. If you have any problems with your furnace this winter, feel free to contact us online or call us at (913)856-5801.
 
Santa Fe Air Conditioning and Heating serves the Kansas City area. For more information, contact us online.