What to Do When Your Heater Blows Cold Air: A Step-by-Step Guide
Troubleshooting a faulty heater yourself before calling our Georgia HVAC technicians
On a cold winter night, there’s little that can be more frustrating than discovering your furnace is blowing cold air.
Before you panic and call your trusted HVAC repairman, there are a few steps you can take to try to troubleshoot the problem yourself. In fact, if you routinely follow some of these steps, you might be able to avoid such an emergency from ever occurring in the first place.
1. Get to Know Your HVAC System
The two main types of heating systems are the forced air duct system (utilizes a blower to push warm air into the vents) and the gravity system (where convection currents circulate warm air).
If you have just moved into your home or have recently installed a new furnace, you might not be familiar with how long it takes for the air in the furnace to warm up. Cold air builds up in the vents when the furnace isn’t in use. It may take several minutes for the cold air to clear out of the vents.
Conversely, if your furnace is older and has endured heavy use during the winter months, parts can loosen or wear out and may need replacing.
2. Make Sure Your Thermostat is Set on “Heat”
It sounds like a no-brainer, but double-check to make sure your thermostat is set on “heat.” You wouldn’t believe the number of calls we get where this is the only problem.
If the thermostat is set on “cool” and the fan is turned on, cold air will obviously come out of the furnace. Consider turning the fan on “auto” so it will only work when the heater is operating.
3. Check the Filter
Probably the most common cause for a heater to blow cold air is a dirty furnace filter. A dirty filter upsets air circulation. Ideally, you should change the filter at least annually or, better yet, every 6 months. Changing the filter is as simple as sliding out the old filter and replacing it with a new one.
4. Check the Vents
Check both inside and outside vents. For instance, make sure furniture is not blocking the inside vents. If snow or ice doesn’t prevent you from inspecting the outside vents, clear them of any dirt, debris or leaves. Don’t forget to check the cold air vents as well.
5. Check the Pilot Light
If your furnace is an older gas heating system, check to make sure the pilot light is on. There should be a continuous gas flow which is indicated by a clear blue flame. This keeps the burners working. A dirty pilot light will not properly light and, in turn, will not provide heat through the burners.
Before you attempt to clean the pilot light, be sure to shut off the thermostat and gas flow. With a small wire brush, carefully clean the hole in the area where the gas is released. Then, blow away the debris with a can of compressed air. Finally, remove any remaining dirt with a hand-held vacuum.
6. Try Rebooting the Computer
If your system is relatively new, there’s a good chance it is computer controlled. Anyone who works with computers knows they sometimes need to be reset or “rebooted.” Turn off the main furnace switch, wait 30 seconds, and turn it on again. The gas should then begin to flow back to the burners.
IMPORTANT NOTE: Whenever you attempt to fix a problem with the heat or AC yourself, you should always shut off the electricity or gas.
If your troubleshooting fails to reveal the cause of the problem, contact Gagne Heating & Air Conditioning for further assistance. We provide expert heating and cooling system service and repair in Alpharetta and throughout the Atlanta area.
