“Why is my furnace blowing cold air?”, a question you may ask once if you have a furnace. It can be frustrating when you heat your home with a furnace in the winter, and it seems not to be working appropriately or consistently. People often don’t know what could be wrong with their furnace because they don’t know how it works. It’s just “that thing in my basement that keeps me warm” during the winter months.
There are several reasons why your furnace may blow cold air, many of which are pretty simple to fix yourself without calling for professional assistance. Scroll down to learn some possible explanations for this problem!
The Thermostat Not Set to Auto or On
If your furnace is blowing cold air, the problem may be right in front of you: the thermostat. People often leave their thermostat set to “off” when they go away for an extended period. It is likely because they are afraid that thieves will turn up their heat and cause a massive energy bill. However, if your thermostat is off, it could negatively affect you and your home’s heating system!
If you have an analog thermostat (the knob kind), make sure to turn it up. If you have a digital screen thermostat, check if any buttons are illuminated or highlighted with green colour. It could be that one of these buttons is “on.”
If you have a digital screen thermostat, make sure that the screen’s arrow buttons point up toward the word “heat” or the “HEAT” bar. Make sure to try turning your thermostat entirely off and then on again, just for good measure.
The Furnace Isn’t Warmed Up Enough
If your furnace blows cold air when you turn it on, it may be because the furnace doesn’t have enough time to heat up. It can happen if you flip the switch and expect instant results. Many modern furnaces take around ten minutes to get warmed up from a completely off state.
To make sure this isn’t causing issues for your furnace, make sure to give it at least 30 minutes before you decide that something is wrong with the heater itself or its settings. Once you’ve given it a longer wait, make sure everything looks correct with the thermostat and consider calling an HVAC professional for problems beyond what we can explain here!
Dirty Furnace’s Flame Sensor
One common reason that a furnace may blow cold air is because of a malfunctioning flame sensor. The flame sensor is the small pointed device on your furnace near where the pilot light would be if you have a gas furnace.
Its purpose is to ensure that gas flows freely and only when the pilot light is lit and produces enough heat for it to sense. If your flame sensor becomes dirty or loose, it may prevent gas flow from reaching your furnace’s elements, resulting in blowing cold air!
To check this:
- Unplug your furnace completely, and then plug it back into the wall.
- Turn your thermostat up and wait 30 minutes, as we mentioned above.
- Once those thirty minutes are up, turn on your furnace again.
If it is still blowing cold air, open up your furnace’s cabinet doors and ensure the flame sensor isn’t loose or dangling. If possible, try cleaning the rod with a clean cloth moistened with rubbing alcohol to remove any dirt causing the gas flow obstruction.
Clogged Furnace’s Air Filter
Another issue that many people ignore until it’s too late is the furnace’s air filter. It is a simple rectangular metal or plastic device that sits inside your furnace and keeps unwanted dust, debris, and dirt particles that can clog up your furnace over time.
It may result in reduced airflow when this happens, which means you’re not getting as much heated air to your rooms! Without enough airflow (and therefore heat), you’re likely to experience the “blowing cold” effect.
Make sure to inspect your furnace’s air filter often during fall months before the weather gets colder every year! Many times all it takes is a good hosing down with water plus some soap to get rid of any excessive buildup.
Is the Ductwork Functioning?
A great way to tell if your heat is working fine or not is by checking the ductwork in your home. If you have any registers/vents on your walls, floors, or ceilings blowing cold air, there’s a good chance something is wrong with the ducts themselves!
If some of these vents are blowing cold air while others are still relatively warm, it may be time to call an HVAC professional. Even if you’re feeling up for the job yourself, it’s always best to call someone who has experience with what could be going wrong with your system before trying out more complicated solutions that you might find online.
Dirty Condensation Pump
If you have checked the air filter, the pilot light, and all of your registers/ductwork but still believe that something is wrong with your furnace’s airflow, it may be time to check out the system’s condensation pump. The function of this small, plastic box is to take any leftover water which may accumulate inside the furnace’s ducts and pipes and then throw it outside through a drain or hole near your house!
Sometimes these pumps become clogged with dirt or other debris, which can cause them to stop working correctly. If this happens, make sure to unplug your furnace right away, remove any dirt or buildup around where the pump goes, and give it a good cleaning before plugging everything back in again.
Why Is My Furnace Blowing Cold Air – Conclusion
While these are some of the more common things that you can check for yourself before calling an HVAC professional, it’s always best to call someone who knows what they’re doing instead of playing around with something as complicated as your heating system.
If nothing seems to work and you’ve tried all of the tricks listed above, there’s a good chance something isn’t working inside of your furnace. It means that it’s time for an expert to take over!