When your furnace is blowing cold air, it’s a sign that something is wrong. Furnaces are designed to heat your home by blowing warm air through a system of ducts. So, if your furnace is blowing cold air, it means that the furnace is not doing its job correctly.
There are several reasons why your furnace may be blowing cold air. One possibility is that the furnace is not getting enough power. This can be caused by a tripped circuit breaker or a blown fuse. Another possibility is that the pilot light is out. If the pilot light is out, the furnace will not be able to ignite the gas and produce heat.
But let’s delve into this issue:
8 Reason Your Furnace Is Blowing Cold Air
1. The heat switch is set to “off”
When your furnace is blowing cold air, it’s likely because the heat switch is set to “off.” This switch is usually located on the thermostat, and it tells the furnace when to turn on and off. If the switch is set to “off,” then the furnace will only blow cold air. To fix this, simply set the switch to “on.”
2. The pilot light is out.
If your furnace is blowing cold air, it’s possible that the pilot light is out. The pilot light is a small flame that ignites the burner in your furnace. When the pilot light goes out, the burner doesn’t ignite, and your furnace doesn’t heat up.
There are several reasons why your pilot light might go out.
- The most common reason is that the thermocouple has gone bad. The thermocouple is a sensor that tells the gas valve when to open and close. If it senses that the pilot light is out, it will shut off the gas to prevent a fire.
- Another reason why your pilot light might go out is that there’s a draft in the room where your furnace is located. This can happen if there’s a hole in the wall or an open window nearby. The draft can extinguish the pilot light.
If your pilot light keeps going out, it’s best to call a furnace repair technician. They can help you troubleshoot the problem and make any necessary repairs.
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3. The blower motor is not working.
If your furnace is blowing cold air, it’s possible that the blower motor is not working. The blower motor is responsible for circulating air through the furnace and into your home. If the motor isn’t working, the furnace can’t circulate air and it will blow cold air.
There are a few reasons why the blower motor might not be working. One possibility is that the motor itself has burned out. Another possibility is that there is an issue with the electrical supply to the motor. If there is no power going to the motor, it can’t run.
If you suspect that the blower motor is not working, you should call a furnace repair technician to diagnose the problem and make the necessary repairs. Trying to repair a furnace yourself can be dangerous, so it’s best to leave it to the professionals.
4. There is a blockage in the flue or vent system.
The flue is the pipe that carries exhaust gases from the furnace to the outside of your home. The vent system is what allows fresh air to enter the furnace to replace the air that is being exhausted. If either of these systems is blocked, it can cause the furnace to blow cold air.
- One way to tell if there is a blockage in the flue is to look at the flame. If the flame is yellow or orange, it indicates that there is incomplete combustion taking place. This can be caused by a number of things, but a blockage in the flue is one of the most common causes.
- Another way to tell if there is a problem with the flue or vent system is if the furnace starts and stops frequently. This is because the furnace is not getting enough air for combustion and has to shut down to prevent damage to the heat exchanger.
If you suspect that there is a problem with the flue or vent system, it is important to have it inspected by a professional. They will be able to determine if there is a blockage and clear it so that your furnace can operate properly.
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5. There is something wrong with the igniter.
The igniter is responsible for igniting the gas in your furnace, so if it’s not working properly, your furnace won’t be able to heat your home. There are a few different things that could be wrong with the igniter, so it’s important to diagnose the problem before trying to fix it.
One possibility is that the igniter is dirty. If there is any dirt or debris on the igniter, it can prevent it from igniting the gas properly. You can clean the igniter yourself with a brush and some compressed air. Just be careful not to damage the igniter while you’re cleaning it.
Another possibility is that the igniter is faulty. If the igniter is cracked or damaged, it will need to be replaced. This is a job that should be done by a professional.
Finally, the problem could be with the gas line. If there is a leak in the gas line, it can prevent the gas from reaching the igniter. This is a serious problem that should be fixed by a professional as soon as possible.
Check the igniter to see if it’s dirty or damaged. If it is, you can try cleaning it or replacing it yourself. If that doesn’t solve the problem, you may need to call a professional to take a look at your gas line.
6. There is something wrong with the burner assembly.
The burner assembly is the part of your furnace that actually burns the fuel to create heat. If the burner assembly isn’t working properly, it can cause your furnace to blow cold air.
There are a few different things that can go wrong with the burner assembly and cause it to malfunction.
- One possibility is that the gas valve isn’t open all the way. The gas valve is what controls the flow of gas to the burner assembly. If it’s not open all the way, then not enough gas will flow to the burner and the furnace won’t be able to create enough heat.
- If the burner assembly is dirty, that can also cause problems. Over time, dirt and dust can build up on the burner assembly and impede its ability to function properly. When this happens, the furnace may not be able to create enough heat and will blow cold air.
Fortunately, if your furnace is blowing cold air because of a problem with the burner assembly, it’s usually a fairly easy fix.
Start by checking the gas valve to make sure it’s open all the way. If it is, then check the pilot light to see if it’s lit. If it’s not, you may need to relight it. And finally, take a look at the burner assembly itself and see if it’s dirty. If it is, you can clean it with a brush or vacuum attachment.
If you’ve checked all of these things and your furnace is still blowing cold air, then there may be a more serious problem and you should call a professional for help.
7. There is something wrong with the heat exchanger.
The heat exchanger is a coil of metal that sits inside your furnace and gets very hot when the furnace is on. The heat from the heat exchanger warms the air that blows out of the furnace and into your home.
But if the heat exchanger is damaged, it can leak carbon monoxide into your home. That’s why it’s important to have a professional inspect and repair your furnace if you think there might be a problem with the heat exchanger.
There are a few things that can cause damage to the heat exchanger.
- One is corrosion. The heat exchanger is made of metal, and over time, it can start to corrode. This can happen if your furnace isn’t maintained properly or if the air in your home is particularly humid.
Corrosion can also happen if the heat exchanger overheats. If this happens, it’s usually because there’s something wrong with the furnace itself, like a blocked vent.
- Another thing that can damage the heat exchanger is physical damage. This can happen if something falls on the furnace or if the furnace is jostled around too much. Physical damage can also happen if the furnace is too old, and parts start to break down.
If you think the heat exchanger may be damaged, it’s important to call a professional for help.
They will be able to inspect the furnace and determine if there is indeed a problem with the heat exchanger. If there is, they will be able to replace it so that your furnace can start blowing warm air again.
8. Because of a problem with the combustion air supply.
If your furnace is blowing cold air, it could be a problem with the combustion air supply. The furnace needs a steady supply of fresh, outside air for proper combustion. If the air supply is restricted or if the furnace isn’t getting enough air, the furnace may not be able to produce enough heat to warm your home.
There are several things that can cause a problem with the combustion air supply:
- The furnace might be located in an enclosed space, such as a closet, garage, or basement. If there’s not enough ventilation in the area, the furnace may not be able to get the fresh air it needs.
- The ductwork that carries outside air to the furnace could be blocked or restricted. Make sure there are no obstructions in the ducts, and that all the vents are open.
- The outside air intake could be blocked by snow, debris, or other objects. Clear any obstructions from the intake so that the furnace can get enough air.
If you’re not sure what’s causing the problem, call a heating contractor or HVAC technician for help. They can inspect your furnace and ductwork to determine if there’s a problem with the combustion air supply.