December 15, 2021
Furnace Repair in Sacramento, CA

During the cold season, heating the house is the only way to make it comfortable enough for your family. It’s simple. All you do is fire up your furnace, and soon, the whole house feels warm again. But what happens if, when you do that, the furnace expels cold air? Here are some insights into what could be wrong.

It Needs Time to Heat Up

If you just fired it up and out comes some cold air, then you’re likely to panic. After all, the temperatures outside are dropping every minute. But if it has been a long time since you last used the furnace, some cold air is normal. After all, your furnace did not save up some warm air for this day. For it to start producing some warm air, it needs time to reach a favorable temperature. Several seconds or minutes, it will start emitting hot air again. Most of the time, you just need a little patience, and everything will be fine.

Typically, there’s a 10 to 15 minutes allowance for this. However, if after this time it’s still producing cold air, then there’s an underlying problem that needs to be addressed. It would be wise to turn the furnace off and get in touch with a pro immediately for help dealing with the issue.

Your Thermostat Settings Are Incorrect

Your thermostat makes it easier for you to define what temperature range is ideal for your comfort. It’s easy to set a range by pressing some buttons. The rest will be handled for you.

So, when the blower is producing chilly air, it would be wise to first check whether you set your thermostat to favorable temperatures. Typically, someone might have unintentionally or accidentally changed the settings during the hot seasons, mainly because you barely used the heater during summer. That’s a normal occurrence, and simple rectification of temperatures will fix the error.

Commonly, your thermostat settings could be set to the “on” setting rather than the “auto” setting. Using any other settings other than “auto” may lead to cold air blowing out of your furnace since the setting instructs the system to expel any available air despite the heat settings being off. Therefore, ensure that you reset it to “auto” if it’s not on that setting already.

But what happens when you reset it correctly, and the system still gives out cold air even after 10 to 15 minutes? When that happens, you should seek professional help immediately.


Furnaces come with a safety feature that automatically initiates an ignition stop when it overheats. Therefore, your furnace will be expelling non-heated air. During that time, the blower will still be on because it cools down the system. Several reasons behind your heating system’s overheating include:

  • Dirt building up in the internal components of your furnace, resulting in clogging
  • Debris and other particles interfering with normal airflow
  • An old furnace with worn-out parts malfunctioning
  • Worn-out or dysfunctional parts affecting movement in the internal components

One or more of these factors could result in structural or mechanical failure amounting to your heater blowing unheated air.

Clogged or Dusty Filtration System

If your central heating system is connected to the heater, then dust and debris will get into the interconnected ducts. Eventually, they will make their way into the vents, clogging the filters. If this happens, airflow will be limited, leading to overheating. And when your system overheats, it will reset by turning off.

Therefore, always ensure that you regularly change or dust the air filtration system, especially after leaving the furnace off during the hot seasons. If you already addressed all the above-mentioned issues yet there are zero improvements, then you ought to check the filtration system to see if it’s clogged or dusty. If changing the filter and cleaning up what you can of the ducts doesn’t help, then it’s time to call in a Sacramento HVAC professional.

Faulty Fuel Supply

Your heating system relies heavily on fuel supply to produce heat. If something cuts or limits that supply, your furnace will not function steadily, thus emitting unheated air. It normally happens if its pilot light is falling or faulty, hindering fuel from reaching the ignition chamber. Alternatively, your fuel tank may be empty, or the gas entry valve is dysfunctional.

Either way, fuel will not be reaching the ignition chamber, amounting to the heat dying off, which in turn leads to unheated air being blown out.

Faulty Fire Detector

Modern home heaters are advanced beyond using pilot lighting to initiate ignition. Rather, they use a flame detector to initiate the heating. But what if your heater’s flame detector is dusty or grime-filled? Then, the heating process will not be initiated, causing unheated air to blow from the heater.

The fault may be rectified by dusting off the ignition sensor. But it’s dangerous to do this yourself. Because of inadequate training and the lack of necessary tools, you may end up causing an accident or causing more damage to your system. Therefore, to fix your problem, seek expert assistance to handle such issues.

Clogging in the Condensate Lines

Another adjustment to modern home heaters is where they use condensate lines for draining moisture from the system. These lines help eliminate moisture produced in the heating system of adjoined AC units preventing rust. But if they’re clogged or faulty, the moisture buildup will result in a furnace shutdown. If this happens, your furnace will blow out cold air since the ignition has shut down.

Cracked Ducts

Cracks or holes in the system ducts could be the factor causing cold air emission. Any openings in these ducts allow hot air to escape while letting cold air in from the surrounding areas. Even with a well-functioning furnace, such leaks interfere with hot airflow. Besides, cold air seeping into the furnace ducts cools down the remaining hot air. If this happens, your furnace will be emitting cold or slightly warm air rather than hot air. The problem can be corrected by identifying the cracks and sealing them to prevent hot air loss or cold air from entering the ductwork. It’s advisable to use expert services to ensure that you catch and seal every last crack in the system ducts.

Your blower might produce unheated air if you switch it up suddenly after not using it for a long while. It commonly happens during cold and snowy seasons. Initially, you may have to give the heater a little more time for things to change. However, if it takes longer than usual, you should call a trained HVAC professional to help you get your system up and running again.

Are you looking for an HVAC expert to assist you with fixing issues with a heating furnace? Gallagher's Plumbing, Heating and Air Conditioning offers the best plumbing and HVAC installation and maintenance services for you in Sacramento, CA, and the surrounding areas. Contact us at Gallagher's Plumbing, Heating and Air Conditioning today for fast and affordable furnace maintenance services.

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