If your furnace is blowing cold air, it could be a sign of mechanical malfunction. However, there are many things that can cause this problem, and mechanical failure is only one possibility. Before you call a furnace service repair company, such as Chappel's Heating & Cooling, to see your unit, perform the following steps to be sure that there isn't a simple fix for your problem.
Check Your Air Filter
Your HVAC system has one air filter for both the air conditioner and furnace. As long as your HVAC system is running, the air filter is cleaning the air that flows through the ducts. The air filter is supposed to be replaced every 3 months or so when the HVAC system is in use, and it needs to be replaced more often if the system is very dirty.
A clogged filter can make it difficult for your furnace to do its job, making the unit run continuously. To prevent the furnace from overheating, a safety mechanism in the unit may cause the burners to shut down, causing the furnace to blow cold air.
Turn off the furnace, then buy a new filter from the home improvement center. Take out the old air filter and insert the new filter into the available slot. If this doesn't fix the problem, move on to the next step.
Check the Pilot Light
The pilot light can go out if there's an interruption of gas service to the furnace. If the pilot light goes out, your furnace won't be able to heat the air. Instructions for locating and relighting your pilot light should be located on the outside of the furnace. If you can't find the manufacturer's instructions on the outside of the furnace, look in your furnace's owner's manual.
Seal Gaps in the Ducts
Leaky ducts can let in cold air while letting hot air escape into parts of your home that you don't want to be heated. You can stop this by inspecting the ducts in your attic. Look for gaps between segments of ducts as well as gaps in the sections where ducts protrude from the wall. If you find gaps, wrap the ducts with duct insulation and tape the insulation to the ducts using foil tape.
If none of these tips help you fix the problem, there's a good chance that your furnace is in need of repair. Contact a furnace repair person to have him or her come to your home and inspect your furnace. Once your furnace is fixed, you can help prevent this problem in the future by having your furnace tuned up at the start of every fall or spring.