If you have a furnace that is blowing cold air out into your home, it could indicate an issue with one of many different components of the appliance. Examples of the impacted components may include the gas supply, the condensate lines, the flame detector, the air filter, or the pilot light. In this comprehensive guide, we are going to outline a total of 10 problems that could result in a furnace pushing out cold air into the home and the associated fixes with each. Continue reading to learn more.

Person staying warm because of a Broken Furnace

1. The Wrong Thermostat Settings

If the thermostat on your furnace is not set properly, you may find that cold air is blowing from the unit. Be certain to verify that the furnace is set on heat. Review the temperature setting to ensure that it turns on heat when heat is required within your home. If there is an “auto” setting, switch the unit to this. This will allow the unit to turn on when it becomes necessary for the home to have more warmth.

2. The Warm-Up Period

If you find that the furnace within your home turns on, but there is cold air or no air coming out, it could be that the unit must heat up. In most instances, these units have a fan limit switch that aids in the warm-up of the system. Once it warms up, the blower of the appliance will then push out warm air through the air ducts throughout the home.

3. The Pilot Light

If your furnace is blowing out cold air and no heat, it could be an issue with the pilot light. Simply look for the appropriate assembly for the pilot light and see if there is a flame on it. If not, you need to light it according to the instructions from the manufacturer. If you light it and it does not remain lit, you should contact a professional.

4. Malfunction of Flame Sensor

If your furnace is blowing cold air and seems to be turning on and off quickly and on a consistent basis, it could be that the flame sensor has malfunctioned. This detects the flame in the burner. If the gas is opened and no flame is detected, this sensor will shut down the furnace. If this malfunctions, it will continue to shut down the furnace even if there is a flame because it is not capable of directly sensing the heat. This will require the aid of a professional.

5. Malfunction of the Fan Limit Switch

If you see an error message, come across the thermostat or you observe a blinking light shining through on the control board, the fan limit switch may be malfunctioning. This measures the temperature of the air in the furnace. If it is not working properly, cold air will blow out of the furnace even when the heater is on.

6. Dirty Air Filter

Believe it or not, something as simple as a clogged or dirty air filter may be to blame for cold air being blown from the furnace. Simply check the thermostat to ensure that it is set to heat and the proper temperature. If so, follow the manufacturer’s instructions for checking your air filter. If you find that it is dirty, replace as instructions outline.

7. Leaking Air Ducts

If there is cold air blowing out of your furnace and you feel warm air around the seals or the joints that are located near the ductwork, it could be that your air ducts are leaking. In most instances, this is an easy fix; however, if you are not comfortable with the job or the steps that you take to resolve the issue are not successful, you will need the assistance of a HVAC professional.

8. Closed Supply Vents

Throughout the year, it is not uncommon for a homeowner to close vents throughout the home that they do not need. In the winter, though, if too many of these are closed off, it could result in the overheating of the furnace. If your system is short cycling – or turning on and off consistently – it could be that the closed supply vents are causing the furnace to overheat. In turn, this may be causing it to blow cold air throughout the home. To resolve, simply open up the vents.

9. Computer Control Issue

If you have a modern furnace, it is quite likely that it includes computerized controls. All operations on these devices are actually managed by a control board that is electronic in nature. For this issue, you will need to have the board evaluated by a HVAC professional. In some instances, this may be done remotely – which means the professional does not even have to come to your home to diagnose the issue, they can do it over the internet.

10. Gas/Oil Supply Problem

If your furnace is blowing out cold air, turning on and off, and even struggling to keep the pilot lit, it could be that you are having a problem with the gas/oil supply. This could be an issue with the line, a clog, or even a problem with the source of the gas or oil that runs into your home. For this type of problem, it is best to start with a HVAC professional. If need be, you may be directed to the gas/oil supplier if the problem is not with your system.

How Do You Fix a Furnace That Only Blows Cold Air?

To fix a furnace that only blows cold air, you should make sure the thermostat is turned to heat and set on the appropriate temperature. Then, you should open and adjust all vents in the home. Inspect the air filter and replace, if needed. If these steps fail to work, you should contact a professional HVAC technician to determine the cause of the issue. Be certain that the professional that you call is both licensed and insured in HVAC so that you and your system are properly protected.

Why is My Furnace Blowing Cold While Set to Heat?

If your furnace is blowing cold while set to the heat setting, it likely means that the heated air is actually escaping before it can make it to the vents throughout your home. If this is the case, it means that there are holes or cracks throughout the ductwork of your home. This means that you will need a HVAC professional to evaluate the ductwork throughout your home and repair as necessary. Once this is done, you will find that the heat is no longer capable of escaping and that your home is warmed properly.

Contact Us Today

Now is the time for furnace maintenance. While most have already turned on their furnace for the season, it is never too late to get that appliance a thorough inspection and to put it on a maintenance schedule. If you have turned on your furnace and feel it is not blowing as warm as it should, we here at Reynolds Plumbing can look it over for you.

We have currently been in business and serving the Richmond and Wayne County Indiana areas for over 40 years. We are licensed, insured, and are capable of servicing both commercial and residential customers. If you need service, we are there for you. Simply give us a call to schedule that which you need. We offer the lowest HVAC and plumbing prices in this area of Indiana. For more information, contact us now at: 765-966-0994

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