You’ve been looking forward to the weather warming up all winter, and perhaps you’ve been excitedly eyeing your central air conditioner while you envision the day when it will be warm enough to turn it on. However, perhaps you’ve noticed an odd phenomenon occurring before that day arrives: you might be feeling cool air inside your home that isn’t coming from your air conditioner at all. Instead, you may have noticed that your furnace is blowing cold air throughout your home before you’re ready for the temperature inside to drop. Besides, who wants a furnace that makes the inside of your house cooler? Probably not you.
The real question when something like this occurs is: should you repair the offending furnace, or replace it entirely? Before you can answer that question for yourself, you’ll have to take a detailed look at your furnace and determine what exactly is happening to it. Fortunately, we can help. Read on, and learn all you need to know about this symptom so that you can determine its cause and take appropriate action to have your furnace fixed.
Different Potential Causes of a Furnace Blowing Cool Air
The truth is, your furnace might be blowing cool air for several distinct reasons. Before you’ll know whether to replace the furnace or simply repair it, you’ll have to identify the nature of the problem. Here are the most common reasons for a furnace to spread frigid air throughout a building. Hopefully, this guide will tell you everything you need to know to make your decision.
- Thermostat Problems
A defective thermostat is often the culprit when it comes to unexpected (and unwanted) temperature changes in the home, so the thermostat should be the first thing you check when your furnace begins blowing cold air. Remember: if your thermostat is ON, your blower fan will continue running—even if the thermostat isn’t set at a temperature that will cause the furnace actually to warm your building. Have a look at the switch. If it’s “ON,” flip it back to “AUTO” and see if the problem stops.
- Dirty Air Filters
Sometimes furnaces begin to blow cold air because they’re overheating and their automatic safety switch has turned on. Overheating is typically caused by poor airflow, and dirty air filters are a predominant cause of poor airflow in most buildings. Check the air filters and see whether they’re dirty. If they are, just replace or clean them. Remember: it’s usually good practice to change out your filters once a month when you’re using your HVAC anyway.
- Problems with Your Pilot Light or Igniter
Most furnaces burn fuel to produce heat, which is impossible if that fuel cannot be ignited. It is the pilot light’s job to ignite the fuel that your furnace uses (or the igniter, in newer models). However, if your pilot light is out or your igniter is broken then it cannot light the fuel, and your furnace will blow chilly air.
- Not Enough Gas
Some furnaces will stop working if their supply of gas is interrupted or the gas is not turned on. Your thermostat may give you the impression that the furnace is running in such cases, but it will not be blowing warm air, and the air that does come through the vents may be roughly the same temperature as the outside. In such cases, it is best to check your gas supply. If it is still turned on, you may have a severed gas line and require a professional to fix it.
- The Ducts Need Professional Care
Air ducts are responsible for carrying the air heated by your furnace through your home. However, a lot can happen to that air along the way, especially if there is a problem somewhere in the ductwork. Leaking ducts are a perfect example. When a channel leaks, cold air from elsewhere in the home (or even the outside) can enter and lower the temperature of the air that has already been heated. If there are numerous leaks, the air may be frigid by the time it leaves the ducts and enters your home. Checking these conduits for leaks is an excellent way to identify this problem—but if you aren’t sure, it never hurts to have them inspected by an experienced and licensed professional.
- Your Furnace is Just Too Old
If your furnace is more than ten years old, fixing the problems listed above might not be worth it. There’s a high chance that something else will just go wrong as soon as you’ve done so. If any of the above problems occur in a relatively new furnace, you can probably solve them by replacing individual components or arranging for duct cleaning. In a decade-old system though, replacement is perhaps the most cost-effective option.
Taking care of your furnace is an essential part of making sure that it always functions as intended. After all, furnaces are complicated systems and numerous problems can cause unpredictable issues. If your furnace is blowing cool air, make sure you check all the areas listed above and see which one might be causing your problem.