A furnace is the centerpiece of your home’s entire heating system. However, a furnace blowing cold air doesn’t contribute anything to this system. In fact, it is actively doing the opposite of what it is supposed to do.
If you’re asking yourself, “Why is my furnace blowing cold air?” keep reading. This article will cover a few common reasons and show how you can approach the troubleshooting process.
There is no single reason that a furnace will suddenly start blowing cold air. Instead, several factors may cause or contribute to the issue.
A Dirty or Faulty Thermostat
Your thermostat is essentially your furnace’s primary sensor. It lets the furnace know when the room is too cold and when it should switch on.
However, it won’t work correctly if your thermostat is dirty or experiencing another issue. It may sense that the room is warm enough even though it isn’t. In this case, it will not tell the furnace to turn on or will tell it to run without warming the air.
Internal Control Board Failure
The thermostat sends its signal to the furnace’s internal control board. Given what the thermostat wants, this board then tells the furnace exactly how to operate it.
However, the internal control board can have issues too. It may get the signal to make the room warmer but may have an issue that prevents it from relaying this signal to the furnace. It may even try to relay the message but do so in a way that doesn’t work. Whatever the issue is, it ends up resulting in the furnace not working correctly.
Your furnace needs a filter to stop dust and other pollutants from getting inside. The filter captures and retains these harmful particles, but if it’s not replaced periodically, they accumulate over time and can cause issues.
The heater will not function correctly if the filter gets clogged with dirt. The accumulated dirt restricts the air passing through the filter, reducing the overall airflow and preventing the furnace from receiving the necessary air to distribute heat.
Clogged Condensate Line
Condensate lines are another critical feature in many modern furnaces. They help deliver any water buildup away from the furnace, where it is disposed of.
However, condensate lines are prone to clogs from dirt and debris like filters. If this happens, the furnace typically senses it and regulates its operation to prevent sending more down the lines. Doing so requires the furnace to operate without producing heat.
The heat from a furnace is created by a flame. This flame starts with the spark from an igniter or the existing flame of a pilot light. Without this initial spark, the rest of the flame is impossible to create. Without the flame, the furnace produces no heat.
If the igniter has a problem or the pilot light is out, the furnace will not ignite. It may still operate, attempting to circulate warm air throughout the area, but since there is no heat source, the air it blows out will remain cold.
How to Troubleshoot a Furnace Blowing Cold Air
The sheer number of potential problems that can strike your furnace makes diagnosing the problems sound impossible. Luckily, there are a few key ways through which you can try to troubleshoot the problem. Going through these methods will get you on the right path for furnace repair.
Check Thermostat Settings
Firstly, check the thermostat settings to ensure they are not causing the furnace to blow cold air. Verify that the settings are appropriately configured to avoid this issue.
The first thing to check is that the furnace is set to “heat” mode and is not set to “fan” mode. Fan mode will just have it blow available air without heating it, which will lead to the heater blowing cold air. Next, check that the temperature is set correctly. If the temperature is set too low, it won’t end up heating the room until it reaches that shallow point.
While this might seem like an obvious solution, it is also something that is easy to overlook. Plus, if the problem is with the settings, you don’t have to worry about anything else. Instead, you just have to adjust the settings.
If your settings are correct, make sure they seem accurate. Use something else to measure the temperature of the room. Then, verify that this temperature matches the reading on your thermostat. It may indicate that something is preventing the thermostat from reading the right temperature if it doesn’t.
Check Air Filters
If your thermostat is alright, you should check your air filters next. First, locate the filter. It should be in an accessible point near the furnace of your actual HVAC unit.
In most cases, you’ll be able to tell if the filter is dirty. It will visibly look like it is filled with dirt and dust. Even if it isn’t, consider replacing it if it has been a while since it was last replaced. If the furnace is not blowing hot air even after a filter change, then the problem is not with the filter.
While you are doing this, check your HVAC system’s manual to see how often you are supposed to replace your filters. In the future, use this as your guide for replacing them.
Call an HVAC Pro
For most other problems, you must call an HVAC pro to diagnose and fix the issue. They will have the knowledge and understanding of an HVAC system to tell exactly why the furnace is not heating. This includes looking at things like your furnace control board, which most people don’t understand.
Once the problem has been identified, it’s crucial to begin the repair process. In most cases, HVAC professionals are needed to fix the issue due to their specialized skills and knowledge. By involving an HVAC pro, you can ensure that the entire process is handled by an expert. If you’re unsure about who to contact, consider searching online. You can locate local service providers and even schedule an appointment through their website.
How Much Does a Furnace Repair Cost?
The ultimate price of furnace repair depends on the exact nature of the issue. Smaller jobs will obviously cost less, while larger ones will cost more.
For example, if the issue is a dirty filter, the biggest cost in repairing it often comes from purchasing a new filter. As new filters are typically not that expensive, a repair like this won’t be that expensive either.
Meanwhile, if the problem is due to an issue with the thermostat or the control board, they may need to be replaced instead. This is more difficult in general and requires more complex and specific parts. Overall, a type of repair like this will end up costing more.
Finally, the most costly job will be one where the furnace has experienced some critical failure and is no longer working. In these cases, furnace replacement is necessary.
In order to determine the cost of furnace repair, you must first identify the specific repair required. Once you have this information, you can collaborate with professionals to obtain a quote for the necessary repairs.
When in doubt, call professionals
If your furnace is blowing cold air, it is a sign that something is not functioning correctly, and it is essential to call professionals for assistance. A professional furnace technician has the experience and knowledge to diagnose the issue accurately and provide the necessary repairs. Attempting to fix the problem yourself can be dangerous and may cause further damage to your furnace. Professionals can identify and fix a range of furnace issues, such as a malfunctioning thermostat, clogged air filters, or a faulty pilot light, restoring your furnace’s function and ensuring your home remains warm and comfortable.
Additionally, scheduling regular furnace maintenance with a professional can help prevent future problems and extend the lifespan of your furnace.