Is Your Furnace Blowing Cold Air? Furnace Troubleshooting

A furnace is a very useful mechanical component during the cold winter months. These HVAC systems are used to keep your family warm and comfortable when the outdoor temperatures drop. While one of these units may go its whole life without having a problem, some furnaces experience an issue at some point.



One of the common problems with these units involves a furnace blowing cold air. As you’re looking for warming relief from the bitter temps, these complications can be incredibly frustrating. Luckily, there are some easy troubleshooting tips that can help. Keep reading to learn more about how to solve this common furnace problem.

Check If The Thermostat Is Working

Your thermostat and furnace work hand-in-hand to provide comfort for your family. If your thermostat isn’t working correctly, it could be the culprit to your furnace blowing cold air. First, head over to your thermostat and examine it to see if it’s working correctly. If it's not, it could be sending the wrong instructions to your furnace system.

If this seems like your problem, replacing your thermostat could be the right decision. There is a chance an HVAC technician could fix your thermostat, but it’s usually more cost-effective to buy a brand new device.

Luckily, a new thermostat is pretty affordable. Also, these units are now extremely advanced and come packed full of features and capabilities. When looking for a new thermostat, consider choosing a smart or programmable option. This allows you to better manage your indoor temperatures and maintain high energy-efficiency levels.

If you go this route, have an experienced HVAC technician install the new thermostat for you. This can ensure everything is set up correctly. If you try the installation on your own, you could cause issues to your thermostat or furnace system. Leave it up to the professionals for the best results.

Check The Thermostat’s Fan Settings

Another troubleshooting tip is to check the settings on your thermostat. On some occasions, these settings could be causing your furnace to blow cold air. First, check to see if your furnace’s blower fan is turned on to run continuously. If that's the case, it will run even when the system isn’t producing any heat. This could be the cause of your furnace blowing cold air.



To troubleshoot, head over to your thermostat and evaluate the fan settings. Check to make sure the fan is set to AUTO, not ON. When the correct setting is used, your heater’s fan will only power on when heat is produced by the system. This process should help eliminate any cold air moving through your home.

Pilot Light Goes Out

Another common culprit to this issue is when the pilot light on the furnace goes out. If this happens, your system may blow cold air because there is no combustion of fuel occurring. The pilot light must be relit to fix this issue.



Here are the troubleshooting steps:

• Remove power from furnace.
• Find the pilot light assembly and turn off the reset switch.
• Allow any remaining gas to escape by waiting 10-15 minutes.
• Set the reset switch to PILOT. Simultaneously, use a match or lighter to ignite the gas coming out.
• If the pilot is lit, crank the switch to ON.
• Restore the power to your heater.

If your pilot light keeps going out or if you can't ignite it yourself, call an HVAC technician for professional furnace repair service.

Examine Furnace Air Filter

Another common issue lies with the air filter of the furnace. If this filter is dirty, it can block the necessary air movement in order for your system to work properly. This inefficiency can increase the temperatures inside the furnace, which can cause your unit to shut down if it gets too hot. Your limit switch will power off the unit if there is excessive heat.

If you have a dirty furnace filter, be sure to replace it. This is one of the most common ways to fix a furnace blowing cold air.

Here are the steps to effectively replace this filter:

• Find the filter compartment on your furnace and remove the access door if needed.
• Remove the dirty filter and throw it away properly.
• Slide in a new, clean filter. Make sure it’s in the right direction.
• Put the access door back into position. Replace this part if needed.



After the furnace cools off, it should be able to restart. If you experience any issues, call an HVAC service business for help.

Damaged Furnace Control Panel

If you have a furnace blowing cold air, the issue could be found in your system’s electronic control panel. On some occasions, simply resetting the unit could solve the problem.



Here is what you can do:

• Power off the system at its ON/OFF switch.
• After waiting a couple of minutes, turn the switch to ON.

If the issue isn’t fixed, call a professional for a furnace repair.

Standing Water Around System

A furnace produces condensation, which typically leaves the unit from the condensate drain line. When this becomes blocked, the overflow kill switch of the furnace will turn off the system to prevent any damage. If you notice standing water around your furnace, it’s a tell-tale sign you have a condensate line blockage.



These clogs can be fixed by following these steps:

• Remove all power from the furnace unit at the breaker.
• Use a wet/dry vacuum to remove any water sitting in the condensate drain pan.
• Take out the drain pan and clean with dish soap and water; then replace.
• Find the condensate drain pipe extending from below the drain pan to outside your home. After locating the opening, attach the vacuum to remove any clogs.
• Turn power back on to your system.

Contact A Trusted, Reliable HVAC Technician

If you’ve tried the tips above and nothing works, your best bet is to call a furnace repair service provider. More often than not, there are furnace experts in your area who can help solve any problems. However, always choose an experienced, certified HVAC professional. If you have a furnace blowing cold air, these experts can fix your system to restore warm comfort for your family.

Not sure if the technicians in your local area are reliable? Give us a call and we’ll connect you with one of our vetted preferred contractors.