Is your furnace blowing cold air? Regardless of the age of your furnace, you can experience problems that leave you unsure of what to do next. Some heating system problems are simple DIY fixes. However, there are times that you need an expert to fix the problem.  If you let things go too long, the result could be frozen pipes or other issues.

How do you know when to bring in a professional? If your furnace is blowing cold air, check these four things first before contacting a professional furnace contractor.

Replace the air filter.

The furnace could be blowing cold air if the air filter has accumulated a significant amount of dirt. When this happens, the furnace’s heat exchanger will overheat. As a result, the furnace burners shut down to protect the heat exchanger. If the air filter appears dirty, put in a new one.

Check the Fan controls.

If you notice that there are times that cold air comes out of your furnace, it may have to do with the fan setting. The fan settings manage the blower. Thus, ensuring that the fan is “on” is essential. The blower is what is pushing air throughout your living space. If the fan is “on,” the blower is going to stay on all day long. What should you do? Change the setting to “auto” instead of “on.” If the setting is on “auto,” the blower will turn off when the furnace is not heating the air.

Is the pilot light lit?

If your furnace is old, it may have a pilot light. If the pilot light goes out, the burners will not ignite. As a result, things may be a little cool in your home. 

Most furnaces will have a label describing how to relight the pilot light. If not, follow these instructions (or refer to the furnace manual):

  • Take off the panels in front of your gas furnace.
  • Turn the round on/off/pilot knob to the “off” position to turn off the gas. Wait for a full five minutes.  You can typically find it low on the furnace. If you have trouble find it, consult the manual.
  • Once the gas has had time to run through the system, turn the knob to Pilot. 
  • Then, hold down the red “Reset” button and light the flame at the pilot light opening with a long lighter.
  • When the pilot light is on, release the pressure on the reset button and turn the knob to “on.”

If you have difficulty lighting the pilot light, contact a professional. There could be an issue with the thermocouple or something else.


To watch a video of a technician lighting the pilot light, see below:

Blocked condensate line?

Is water gathering near the furnace? Is the furnace a high-efficiency model? There could be an issue with the condensate line, meaning that the furnace will not work correctly. High-efficiency furnaces have a drain line that has the potential to get blocked. When that happens, the furnace shuts down to escape damage from the water.

There are several reasons that the condensate line could get blocked, including dirt, dust, ice, and mould. It could also be that the pump is broken, which would require the services of a professional. What should you do? You can clean the condensate log of dirt, dust, or mould. Ice is a little different. In that case, you would need to wrap heat tape and pipe insulation around the line.

By ensuring that your furnace is cleaned and undergoes maintenance regularly, you can avoid many problems. If your system is due to be looked at, don’t wait for an issue to crop up. Go ahead and have it serviced so that it stays in good working order. In doing so, you may be able to prevent common problems, like cold air coming out of the furnace.