Why is my Furnace Blowing Cold Air?

Furnaces blowing cold air is quite common and despite a furnace being brand new there can be some unpleasant surprises. There are a few problems that you can fix but calling for professional HVAC assistance is always a good call. Trying to save money by not calling a professional right away can result in a huge loss (both money and time) in the long run. Remaining calm and figuring out the best possible solution would be the best bet in this situation.

Reasons For A Furnace Blowing Cold Air

1. Thermostat Issues – An improper thermostat setting is one of the most common reasons why your furnace might be blowing cold air. In case the thermostat fan setting is changed from AUTO to ON, the fan will just continue to run, but will not produce any heating. Once the setting is turned back to AUTO, the furnace will start providing heat again. Also, in case the thermostat has been installed recently, by an amateur, it’s possible that the unit may not be compatible with the heating system. Try hiring an HVAC professional to check out your system. In case the thermostat is quite old, its battery may be running low. Changing the batteries will resolve this issue.
2. No Oil – In case yours is an oil-fired furnace, it could start blowing cold air when it runs out of fuel. The blower would keep circulating the cold air even when the burners would not light and/or produce heat.
3. Computerized Controls – All the new-age furnaces come with an electronic control panel and you might need to reset the system to stop the flow of cold air. So first turn off the furnace using the power switch. Start it up again after a few minutes. It’s almost like fixing a glitch on any computer system. In case, this does not solve the issue, it would be smart to call in professional help.
4. Furnace Overheating – Replacing air filters is an important part of keeping your furnace functioning optimally. Clogged-up air filters can result in your furnace overheating and in turn, turning the burner off, thus stopping the hot airflow.
5. Pilot Light – Older furnaces all have a pilot light that stays on all the time. Something as simple as a strong gust of wind can blow the pilot light out stopping the flow of hot air. Even though it is advisable, it is not absolutely necessary to call a professional in this case, as just relighting the pilot light will do the trick.
6. Valve Issues – Pilot lights simply refusing to light may be a sign that you have issues with your valves. If you have a dirty system that has not been cleaned in a while things like dirt, debris, and other problematic materials can get stuck in your valves(s). It would be a wise decision to have an HVAC professional check out your system.
7. Thermocouple Problems – In case a pilot light can be lit but has the tendency of going out, your thermocouple (a sensor controlling both the ignition and the gas valve) should be checked immediately. A faulty one is the most likely cause of cold air blowing out of your furnace, in this case. A technician can easily adjust or even replace your thermocouple (if needed).
8. Oil Filter Clogging – The filter of an oil-fired furnace can easily get clogged with dirt and debris, similar to the air filter getting blocked in a gas-fired furnace system. The ignition is affected when there is a clogged filter and there will be no production of hot air. Repairing and/or replacing the filter is quite complicated and extremely messy, so letting the professionals handle this job would be advisable.
9. Problems with Electronic Ignition – Modern furnaces are fitted with electronic ignition systems, like an intermittent pilot, or hot surface ignition, etc. The system might be in need of adjustments or repairs or replacement of old components. An HVAC professional can fix this problem easily.
10. Leaks in the Ducts – Leaks in your ductwork can be the reason why all the hot air produced by your furnace escapes and all you get is cold air blowing from the air vents. This would mean that you must conduct a thorough inspection (preferably by a professional) of your entire duct network and the furnace itself, to find all the leaks. Too many leaks may mean replacing the entire network of ducts.
11. Flame Sensor – The flame sensor might have complications as well. If you feel your furnace starting to blow warm air but then quickly shifts to blowing only cold air, it’s like a flame sensor issue. In case the flame sensor is completely covered in grime, or if it is damaged in any way, or it’s worn out, it can cause the burner to switch off. Getting a professional checkup would be the best choice in this regard.
12. Unclean Burner – In case the burner (gas or oil) of the furnace receives a lot of negligence, debris, dirt, grime, etc., that can cause complications during igniting, leading to the production of cold air.

The Massive Importance Of Regular Maintenance

Arguably most of the root causes of furnace problems can be completely eliminated through regularly-scheduled maintenance and cleaning. Regular check-ups mean that any new issues that may be cropping up will be detected early on and the HVAC professional doing the checkup has the means to get the damaged component(s) repaired or replaced. All HVAC service providers offer a lot of maintenance services in their packages whenever they sell any unit. It would be a prudent decision to know about all the services in detail and make sure that all the services are fully utilized.

Ending Note

There can be a number of reasons why your furnace might be blowing cold air, as mentioned above. Doing a thorough checkup to diagnose the problem is arguably the first step in the process of resolving the issue. There are loads of contractors who offer maintenance, check-ups, and other such services, at affordable rates. So you can easily ask for professional help and get your heating system fixed immediately.