Why Is My Furnace Blowing Cold Air?

If you notice your furnace blowing cold air, it’s safe to say it isn’t doing its job. Even in warmer places like here in Phoenix, it’s important to have a working furnace for those days when it does get a little bit chilly. It can be extremely frustrating when you turn on your furnace to heat up the home, and all it does is blow cold air on you. The good news is that there’s almost always a relatively simple solution to this problem, and either you or a Phoenix HVAC professional will be able to get your furnace functioning properly again soon.

Causes and Solutions for Furnace Blowing Cold Air

There are many possible reasons your furnace is blowing cold air. You may be able to fix some of them yourself, while you may need to call an HVAC professional for some of these issues. While the list below will help you narrow down the possible reasons your furnace could be blowing cold air, sometimes the fastest solution is to call a Phoenix furnace repair company as soon as you notice the problem. That way, you’ll be able to rest assured that a professional is finding the fastest way to get your home warm again.

With that said, here are 15 possible reasons your furnace is blowing cold air.

1 – Problems with the Burner

In many cases, your furnace burner could be failing to ignite because it’s too dirty. Dust and other contaminants build up over time, and it may eventually get to the point where the system can no longer ignite. If the flame can’t ignite, your system won’t be able to produce heat. You may be able to carefully clean the burner yourself, but the safest and most effective thing to do is call an HVAC company, especially if you’re not completely sure that this is the issue. Better yet, prevent this problem by having your furnace inspected and cleaned at regular intervals.

2 – Bad Flame Sensor in Furnace

If the furnace starts to blow warm air, but then it gets cold shortly after turning on, the problem may be with your flame sensor. Essentially, the burner is shutting off because the flame sensor is either worn out and malfunctioning, or it’s covered with dust and dirt. If this happens when you try to use the furnace for the first time in a while, it’s even possible that some sort of bug or pest has gotten inside of your furnace and interfered with the sensor. Call an HVAC contractor to get to the bottom of the issue.

3 – Faulty Ignition

Newer furnaces may use an electronic ignition, while older furnaces use a direct spark. Either way, these components can occasionally fail, which will prevent your system from firing up. You may need a new furnace ignition, or you might just need to have your current one repaired or adjusted.

4 – Leaking HVAC Ducts

If your furnace appears to be working, but the air is still coming out cold, it’s probably because the heat is escaping before the air can come out of your vents. In other words, there are holes in your ducts that allow hot air to get out. In this case, you’ll need to get work done on your HVAC ducts.

5 – Failing Thermocouple

The thermocouple is a sensor that controls the gas valve and ignition in your furnace. If it’s faulty, it will cause your furnace to keep going out even if you’re able to re-light the pilot. This is difficult to fix yourself, but an experienced HVAC technician will be able to repair or replace your thermocouple quickly.

6 – Filter Clog in Furnace

The air filter on your gas furnace or oil-fired furnace can get clogged, restricting airflow. You may be able to clean or replace the filter yourself, but this job can get messy if you have an oil-fired furnace. Whether you do it yourself or call a pro, you’ll have to address the filter before your furnace can ignite properly.

7 – Computerized Control Malfunction

If you have an electronic control panel for your furnace, try resetting the system. Turn it off, wait a while, then turn it back on (just like rebooting a computer). If this fixes the problem, great! If not, call for help.

8 – Furnace Overheating

If the furnace starts to overheat, it will shut off for safety reasons. One common reason for an overheating furnace is that the air filter is dirty or clogged, so try changing that to see if it helps.

9 – Valve Issue in Furnace

Valve problems are normally to blame when your pilot light doesn’t come on at all (especially if the ignitor is working). Either the gas valve is faulty, or it’s just too dirty. Have it checked and cleaned by an HVAC professional.

10 – Pilot Light Not Working

Check the pilot light. If it’s out, that’s why your furnace is blowing cold air. Sometimes the light just blows out, but it could also be a sign of another problem. If you know how, carefully try re-lighting the pilot. If you’re not comfortable with that or run into problems, call a Phoenix furnace repair company.

11 – No Fuel for Furnace

If you have an oil-fired furnace, you could be out of fuel, or if you have a gas furnace, it could be having a problem getting gas. Either issue would cause your furnace to blow air without heating it. Try adding new fuel to your oil-fired furnace or calling an HVAC professional who can see if your system is getting proper fuel.

12 – Furnace Not Warmed Up

If you’ve just turned on your furnace and you get a gust of cool air, give it a minute. It’s possible that you’re just getting cool air because the furnace hasn’t had time to heat up yet, especially if this is your first time using it in a while. Even after your furnace starts to get hot, it still has to push all of the cool air out of your ducts before it can start delivering heated air to the home. This is just like how it might take a minute for your shower to get hot. If you’re still getting cold air after several minutes, though, it’s time to schedule a service call.

13 – Bad Thermostat Setting

This problem is especially common in houses with teenagers. If you or someone else has changed the thermostat, that could be why you’re getting cold air. It’s possible that someone could have lowered the temperature on the thermostat or changed the setting from “Auto” to “On.” Either way, just reset the thermostat to the appropriate controls. If this resolves your issue, congratulations, you just fixed your gas furnace all by yourself.

14 – Clogged Condensate Drain Line

High-efficiency furnaces that have been built in recent years often come with drain lines to get rid of condensation. Basically, there is some water that comes from the heating process, and that water needs a place to go. If the drain line gets clogged, it may flip a switch that stops the furnace from lighting, so it doesn’t get flooded with water.

15 – Bad Fan Limit Switch

If the air coming from your vents blows hot at some times but cold at other times, it could mean you’re having a problem with your fan’s limit switch. This switch controls when the fan goes on and off during heating cycles, and a malfunction could have the fan running when the furnace isn’t hot. It may be possible to adjust the limit switch’s settings so the fan won’t blow cold air into your home, or the component may just need to be replaced completely. Either way, you should call your local furnace repair company to address this issue.

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Furnace Repair Phoenix

At Day & Night, we’re Phoenix’s best furnace installation, repair, and maintenance company. When you call us, you’re giving yourself the best service that will get your furnace blowing warm air again as soon as possible. Best of all, we’re guaranteed to be available whenever you need us. Our contractors are on call 24/7/365, and they can give you a free estimate with no strings attached. They’ll also give you their honest, professional opinion about whether it’s better to repair or replace your furnace. As soon as you approve the quoted price, they’ll get to work to get your furnace up and running again.

Furnace Tune Up

The only thing better than a fast furnace repair is not needing one in the first place. To keep your furnace in peak operating condition, we recommend that you schedule regular maintenance. This will allow a professional HVAC technician to inspect your furnace and address problems before they cause your furnace to blow cold air. Furthermore, they’ll be able to clean some furnace components to prevent many of the problems on the list above. We offer multiple heater maintenance plans that come with bi-annual checkups to keep your furnace blowing warm air. Should your Phoenix furnace go out, we also offer Phoenix furnace installation.

Contact Day & Night Air Today!

If you’re having furnace issues that you can’t solve yourself, we’re happy to help. Reach out today, and we’ll send someone to you as soon as possible. Better yet, have an HVAC contractor from Day & Night Air come do a heater inspection before problems arise. They’ll survey your furnace for issues, and this proactive approach will keep your furnace running more efficiently and help it last longer. Contact us to schedule an appointment.