Why Is My Furnace Blowing Cold Air?

November 1, 2021 | Heating, Homeowner Tips

By this time of year, most people have fired up their furnaces and are enjoying the toasty heat in their homes. But what if you notice that your furnace is starting to blow cold air instead? Read on to see what some of the common issues may be.

Check Your Thermostat

One of the easier problem sources to fix could be your thermostat. The thermostat is responsible for communicating to the furnace unit and tells it to slow down or work harder. If the thermostat is broken, then the furnace isn’t receiving the proper instructions. Double-check to make sure the batteries are still working. If you feel like the batteries aren’t the problem, call a Mattex technician to come take a look. Another thing to check on the thermostat is the fan setting. The fan setting on the thermostat controls the blower in the furnace, which moves air throughout your home. If the fan setting is set to ON, then the blower will run continuously even if the air isn’t being heated. In most cases, the fan setting on your thermostat should be set to the AUTO position.

Dirty Air Filters

For most furnace filters, it’s a good idea to get into the habit of changing them every 1-3 months. What happens if you don’t change them on a regular basis? One result could be your furnace blowing cold air. If your filter is dirty enough, it can actually block the airflow in the furnace and cause it to overheat. For safety reasons, this causes the furnace burners to shut off so further damage doesn’t occur. If you think it has been a while since your last air filter change, make this one of the first things you check. Then call us because your furnace may need to be reset.

Blocked Condensate Line

If you notice pooling water surrounding your furnace, it could be tied to your condensate line being blocked. The condensate line is responsible for draining any condensation that accumulates from heating and cooling. It is usually a PVC pipe that leads outside. Dust, dirt, mold, and ice are common causes of these blockages. A broken condensate pump could also be the problem. If you notice pooling water around your furnace, don’t hesitate to give Mattex a call!

Pilot Light Is Out

This could be an issue for older systems especially. If you notice that the standing pilot light on your furnace is out, this could be a good indication as to why you aren’t getting any warm air. The first thing you should try is re-igniting the pilot light. If your pilot light won’t stay lit, you should call one of our technicians. This could mean a gas valve that has gone bad or is stuck from dirt and debris.

Leaky Ductwork

Leaks in the ductwork allow the heat to escape which means your home won’t be heated efficiently. You may notice that one room is colder than the other, or that your energy bill is high. Leaky ductwork also leads to poor air quality in the home.