Why Is My Furnace Blowing Cold Air? Here’s What To Do

Last Updated on November 25, 2023 by Kimberly Crawford

If your furnace is blowing cold air, you may be wondering what is wrong. It can be frustrating when your heating system isn’t working properly, and it’s important to take action quickly to fix the problem.

In this blog post, we will discuss some common causes of a furnace blowing cold air and what you can do to correct them. We will also provide tips on how to keep your furnace running smoothly all winter long!

In this article

Why is a furnace blowing cold air?

Not getting enough fuel is one of the main reasons your furnace may be blowing cold air. If your furnace isn’t getting enough fuel, it will not be able to generate heat. Make sure you are checking your furnace’s filters regularly and changing them when needed. Also, be sure that the furnace is properly vented to the outside of your home.

1. Pilot light is out

If your furnace is blowing cold air, the first thing you should do is check to see if the pilot light is out. If it is, you can relight it following the manufacturer’s instructions. If the furnace still isn’t working properly after relighting the pilot light, you may need to call a technician.

2. Bad thermostat

A bad thermostat can cause your furnace to blow cold air.

You can test the thermostat by turning it off and then back on. If the furnace still blows cold air, the thermostat is bad and needs to be replaced.

You can also test the furnace by turning it off and then on. If the furnace does not turn on, there may be a problem with the furnace and you should call a technician.

If you are having this problem, be sure to call a furnace repair technician to come and take a look at it. A bad thermostat can also cause your furnace to run constantly, which can lead to high utility bills.

So if you’re experiencing any of these problems, be sure to call a furnace repair technician right away. Thanks for reading! furnace, furnace repair, thermostat, utility bills.

3. Faulty Circuit Control Board

One of the most common reasons a furnace will blow cold air is because of a faulty circuit control board. The furnace control board is responsible for sending power to the furnace to heat your home. This component controls the ignition, fan speed, and gas valve. If it isn’t working properly, your furnace may not heat correctly.

If you think your furnace’s circuit control board may be to blame for blowing cold air, it’s best to call a professional for help. Trying to repair this component on your own can be dangerous.

4. Overheat protection

Overheat protection is one of the most important safety features on a furnace. If the furnace overheats, it can cause a fire.

The overheat protection shuts off the gas to the furnace if the temperature gets too high. This can happen if the blower isn’t working properly or if there is something blocking the airflow.

5. Faulty main limit switch

A faulty main limit switch is the likely culprit if your furnace blows cold air. This switch is designed to stop the flow of gas to the burners if things get too hot, but it can fail and cause your furnace to blow cold air.

If this is the problem, you’ll need a technician to come out and replace the limit switch. In the meantime, you can try to reset the switch by turning off your furnace at the breaker box for a minute or two and then turning it back on. If that doesn’t work, you may need to call a technician.

6. A cracked heat exchanger

A cracked heat exchanger is the most common reason for a furnace to blow cold air. The heat exchanger is a metal chamber that contains the combustion process and transfers heat from the burning gas to the circulating air.

If the heat exchanger cracks, hot gases can escape into the ductwork and cause serious problems, including fires. If you suspect your furnace has a cracked heat exchanger, call a qualified technician to have it repaired.

You can also help prevent a cracked heat exchanger by having your furnace serviced and tuned-up regularly. A good maintenance routine will include checking the exchanger for cracks or other damage. If you have an older furnace, it’s especially important to have it checked every year, since heat exchangers tend to wear out over time.

7. A dirty filter.

A dirty filter can cause your furnace to blow cold air. Be sure to change your filter regularly to ensure optimal performance of your furnace.

If you’re not sure when to change your filter, most filters have a lifespan indicator on them. When the time comes, be sure to replace your filter with a new one of the same size and type. You can also consult your furnace’s owner’s manual for more specific instructions.

In some cases, a dirty blower wheel can also cause your furnace to blow cold air. The blower wheel is responsible for circulating air through the furnace. If it becomes dirty, it can reduce the amount of warm air that circulates through the furnace.

To clean the blower wheel, you’ll need to access the interior of your furnace. Once you’ve located the blower wheel, use a brush or vacuum attachment to remove any dirt or debris.

If your furnace is still blowing cold air after you’ve checked the filter and blower wheel, it’s possible that there’s an issue with the furnace itself. In this case, it’s best to call a professional for assistance. A trained technician will be able to diagnose and resolve the problem quickly and efficiently.

8. Closed vents.

Closed vents are one of the most common reasons why your furnace may be blowing cold air.

It’s important to keep all of your vents open in order to maintain a proper airflow throughout your home. If you’ve been noticing that your furnace is blowing cold air, it could be due to the fact that some of your vents are closed. Make sure to check them all and keep them open so you can stay warm this winter!

9. Clogged coil

Clogged coil can cause the furnace to blow cold air. You can prevent this by cleaning the coil every year.

You can also call a professional to clean it for you. They will have the proper tools and knowledge to do the job right.

10. Motor capacitor failure

Motor capacitor failure is one of the most common reasons a furnace will blow cold air. The capacitor is responsible for providing the initial burst of energy needed to start the motor. If it fails, the motor won’t be able to start and the furnace will blow cold air.

11. Thermistor failure

Thermistor failure is the most common reason a furnace blows cold air. The thermistor is a small sensor that measures the temperature of the air in the furnace. If it fails, the furnace won’t be able to maintain the correct temperature, and will blow cold air.

If you suspect that your furnace’s thermistor is failing, you should call a qualified HVAC technician to diagnose and repair the problem.

They will be able to test the thermistor and, if it is indeed failing, replace it with a new one. This is a relatively simple and inexpensive repair that should fix the problem and have your furnace blowing warm air again in no time.

12. Flame sensor

A flame sensor is one of the most important parts of a furnace. It is responsible for detecting whether or not there is a flame present and sending a signal to the control board accordingly. If the flame sensor is dirty or damaged, it can cause the furnace to blow cold air.

The first step in troubleshooting this problem is to clean the flame sensor with a wire brush or sandpaper. If that doesn’t work, you may need to replace the sensor.

Why is cold air coming out when the heat is on?

There are a few reasons why your furnace might be blowing cold air when the heat is turned on. One possibility is that there is something blocking the airflow, such as a dirty filter or a blocked vent. If this is the case, you’ll need to clean or unblock the obstruction in order to get the heat flowing properly again.

Another possibility is that the furnace itself isn’t generating enough heat. This could be due to a problem with the pilot light or igniter, or it could be a sign that the furnace is getting old and needs to be replaced. If you’re not comfortable troubleshooting the issue yourself, it’s best to call in a professional to take a look.

In some cases, cold air could be coming from the vents even though the furnace is working properly. This might happen if your thermostat is set to “fan only” instead of “heat.” Be sure to check your thermostat settings before assuming there’s a problem with the furnace.

If you’re still having trouble getting the heat to work properly, it’s always best to call a professional for help. They can diagnose the problem and recommend a solution.

Furnace intermittently blows cold air.

This can be caused by a variety of issues, such as dirty filters, a blocked vent, or something else. If your furnace is blowing cold air, you should have it inspected by a professional to determine the cause and fix it.

Blowing cold air is not only uncomfortable, but can also be dangerous. It’s important to get this issue fixed as soon as possible.

Why is my furnace blowing cold air sometimes?

There are a few reasons why your furnace might be blowing cold air sometimes. One possibility is that the furnace is not getting enough power. Another possibility is that the furnace is not igniting properly. If you’re not sure what the problem is, it’s best to call a professional to take a look at it.

Why is my gas furnace blowing cold air and won’t shut off?

One possible reason for your gas furnace blowing cold air and not shutting off could be that the pilot light is out. If the pilot light is out, then the furnace will not be able to produce heat.

Another possibility is that the thermostat is set to “off” instead of “heat.” Be sure to check both of these things if your gas furnace is not shutting off.

If you determine that the problem is neither the pilot light nor the thermostat, then it is possible that there is something wrong with the furnace itself and you will need to call a technician.

How do I relight the pilot light on my gas furnace?

If your gas furnace has a pilot light that has gone out, you will need to relight it in order to get the furnace working again. Follow these steps to relight the pilot light on your gas furnace:

-Find the pilot light. This is usually a small knob or lever near the bottom of the furnace.

-Turn off the power to the furnace. This is usually done by flipping a switch near the furnace.

-Wait a few minutes for the gas to dissipate.

-Locate the igniter. This is usually a small button near the pilot light.

-Push and hold the igniter until you see the pilot light start to glow.

-Release the button and continue holding the pilot light until it stays lit on its own.

-Once the pilot light is lit, turn on the power to the furnace and set the thermostat to “heat.”

If you follow these steps and are still having trouble relighting the pilot light, then you may need to call a technician.

Why is my furnace blowing hot air then cold?

One possible reason for this issue is that the furnace’s blower motor may be failing. If the blower motor is failing, it will cause the furnace to blow hot air for a short period of time, and then cold air.

Another possible reason for this issue could be that there is something blocking the flow of air from the furnace to the rooms in your home. If this is the case, you will need to remove whatever is blocking the air flow in order to fix the issue.

Why is my oil furnace blowing cold air?

There are a few possible reasons why your oil furnace might be blowing cold air. One possibility is that the furnace isn’t getting enough fuel. Another possibility is that there’s something blocking the airflow to the furnace. Finally, it’s also possible that there’s something wrong with the furnace itself.

If you think that your furnace might not be getting enough fuel, you can try increasing the fuel flow to the furnace. You can do this by turning up the thermostat or by opening the oil tank’s valve more.

If you think that there might be something blocking the airflow to the furnace, you can try cleaning or removing any obstructions.

Finally, if you think that there might be something wrong with the furnace itself, you should contact a technician to have it inspected.

Why is my new furnace blowing cold air?

There could be a few reasons why your new furnace is blowing cold air. One possibility is that the furnace isn’t properly sized for your home. If the furnace is too large, it will short cycle, which means it will turn on and off frequently and won’t be able to heat your home adequately.

Another possibility is that there’s something blocking the airflow to the furnace. Check your air filters and make sure they’re clean and properly installed. If you’ve ruled out those possibilities, it may be time to call in a professional to take a look at your furnace.

Why is my electric furnace blowing cold air?

There are several possible reasons:

The furnace filter may be dirty or clogged, which is preventing warm air from circulating.

The thermostat may be set too low, so the furnace isn’t turning on even though it’s cold in the house.

The heating elements may be burned out and need to be replaced.

If you suspect any of these issues, it’s best to call a furnace repair technician to take a look. Trying to fix an electric furnace can be dangerous if you don’t know what you’re doing.

In the meantime, you can try putting a space heater in the room where the cold air is coming from. Just make sure to keep an eye on it so it doesn’t start a fire.

Why is my RV furnace blowing cold air?

There are a few potential reasons why your RV furnace is blowing cold air. One possibility is that the furnace filter needs to be replaced. If the filter is dirty or clogged, it can prevent warm air from circulating through the unit, resulting in a cold blast of air.

Another possible issue could be a problem with the furnace motor or blower. If the furnace is not receiving enough power, it will not be able to generate heat.

Finally, there could also be a problem with the thermostat setting or wiring.

Make sure that the thermostat is set to “heat” mode and that all wires are properly connected. If you have checked all of these things and your furnace is still blowing cold air, it may be time to call in a professional for assistance.

Why is my furnace blowing cold air after a power outage?

There are a few possible reasons why your furnace may be blowing cold air after a power outage.

One possibility is that the power surge caused damage to your furnace’s internal components. If this is the case, you will likely need to have your furnace serviced or replaced.

Another possibility is that there was insufficient fuel in your furnace’s tank when the power went out. When the power is restored, the furnace will attempt to burn off the remaining fuel, which can cause it to blow cold air.

If this is the case, you will need to add more fuel to your furnace’s tank. Finally, it is also possible that something is blocking your furnace’s exhaust vent. This can cause the furnace to blow cold air, as it will not be able to expel the heat it generates. If this is the case, you will need to clear the obstruction from your exhaust vent.

If you are unsure of what is causing your furnace to blow cold air after a power outage, please contact a qualified HVAC technician for assistance. They will be able to diagnose the issue and provide a solution.

Why is my furnace blowing cold air only at night?

There are a few reasons this could be happening.

One possibility is that the furnace isn’t getting enough power to run properly. Check to make sure the power switch is turned on and that the circuit breaker hasn’t tripped.

Another possibility is that the furnace’s pilot light has gone out. relight it following the instructions in your owner’s manual.

One possibility is that the furnace filter needs to be replaced. A dirty or clogged filter can reduce airflow and cause the furnace to work harder, leading to increased energy costs and possible damage to the unit.

Another potential issue could be that the thermostat is set too low. If the thermostat is set below the room temperature, the furnace will not turn on and blow warm air. Finally, it could be that there is a problem with the furnace itself.

If the furnace is blowing cold air should I turn it off?

No, you should not turn off the furnace. If the furnace is blowing cold air, it means that there is something wrong with the furnace and it needs to be fixed. Turning off the furnace could make the problem worse. Instead, call a technician to come and fix the furnace.

If your home does not have central heating, you should use a space heater to keep warm. Space heaters are safe to use, but you need to be careful not to leave them on when you go to bed or leave the house. Make sure that the space heater is in a well-ventilated area and that it is not too close to anything that could start a fire.

How To Troubleshoot Furnace Blowing Cold Air

If your furnace is blowing cold air, there are several possible culprits. First, check to see if the furnace is actually turned on. If it is, then check the thermostat to see if it is set to “heat” mode. If both of these things are in order, then you may have a problem with the furnace itself.

The most common problems with furnaces are dirty filters, a clogged air intake, or a faulty igniter. You can troubleshoot these problems by following the steps below:

Change the furnace filter if it is dirty.

This is the simplest and least expensive solution.

Dirty filters restrict airflow and make the furnace work harder, costing you more in energy bills. Filters should be replaced every month or two, depending on use.

If your filter is visibly dirty, it needs to be changed. If it’s not dirty but you’ve had it for a while, change it anyway – better safe than sorry!

Check the air intake to make sure it is free of debris.

If there is debris, remove it. If the air intake is blocked, the furnace will not work properly.

If you have a gas furnace, be sure to check the air intake to make sure it is free of debris. Debris can block the airflow and prevent the furnace from working properly. Remove any debris that you find and ensure that the air intake is clear.

Additional tips:

-Check the air filter monthly and replace it as needed. A clean air filter will help to improve airflow and prevent potential problems with your furnace.

-Schedule an annual maintenance checkup for your furnace. This will help to ensure that your furnace is in good working order and that all components are functioning properly.

If the furnace has an igniter, check to see if it is working properly. You can do this by holding a lighter up to the igniter and seeing if it sparks.

If the igniter is not working properly, you may need to replace it.

If your furnace does not have an igniter, check the pilot light. If the pilot light is out, you will need to relight it. To do this, follow the instructions in your furnace’s owner’s manual.

Once you have checked the igniter or pilot light, try turning on the furnace. If it still does not work, you may need to call a technician.

If you have tried all of these things and your furnace is still blowing cold air, then you may need to call a technician to fix the problem.

Tips on how to keep your furnace running smoothly all winter long

There are a few key things you can do to keep your furnace running smoothly all winter long.

First, make sure your filter is clean and replaced when needed.

Second, check the insulation around your doors and windows to make sure there is no air leakage.

Finally, schedule regular maintenance checks with a qualified technician.

By following these tips, you can help ensure that your furnace will run smoothly all winter long.

How To Prevent Furnace Blowing Cold Air in the future

One of the most common problems with furnaces is that they start blowing cold air. This can be a real pain, especially in the middle of winter. Luckily, there are some things you can do to prevent this from happening in the future.

First, make sure that your furnace is properly maintained. A well-maintained furnace is less likely to have problems with cold air.

Second, if your furnace does start blowing cold air, don’t panic. Turn it off immediately and call a professional for help.

Doing these two things should help you prevent furnace blowing cold air in the future. Remember, a well-maintained furnace is the key to keeping your home warm and comfortable all winter long.

How do you reset a furnace that blows cold air?

If your furnace is blowing cold air, it may be due to a variety of issues. Before resetting your furnace, you should first check to see if the problem is with the thermostat or the furnace itself.

If the problem is with the thermostat, you can simply reset it and see if that fixes the issue. However, if the problem is with the furnace, you will need to reset it in order to fix the issue.

To reset your furnace, you will need to turn off the power to it and wait for a few minutes before turning it back on. Once the furnace has been turned back on, check to see if the problem has been fixed. If not, you may need to contact a professional for further assistance.

Honeywell thermostat blowing cold air on heat setting.

Checked the breakers and they are all on. Set the thermostat to heat and the furnace kicks on but only blows cold air. Tried setting it to emergency heat and still only blows cold air. What could be causing this?

One possible reason for your Honeywell thermostat blowing cold air could be that the batteries are low. Check to make sure the batteries are installed correctly and have enough charge. If they do, you may need to replace the thermostat.

Another possibility is that there is something blocking the air flow in your furnace. Make sure there is nothing obstructing the vents and that all of the filters are clean.

If neither of those solutions work, you may need to call a professional for help. They will be able to diagnose and fix the problem quickly.

Conclusion

In conclusion, if your furnace is blowing cold air, there could be a few different issues at play.

First, check to see if the pilot light is lit. If it’s not, relighting it may solve the problem. If the pilot light is lit but the furnace still isn’t working, there could be an issue with the thermocouple.

Replacing the thermocouple is a relatively easy and inexpensive fix.

Finally, if your furnace is still blowing cold air after checking the pilot light and thermocouple, it’s likely that there’s a problem with the blower motor.

Replacing the blower motor is a more complex repair, so you may need to call in a professional. But don’t despair – with a little troubleshooting, you should be able to figure out what’s wrong and get your furnace up and running again in no time!