Why is my furnace blowing cold air?

Your furnace works day in and day out during the winter to keep you and your family warm when outdoor temperatures dips to frigid temperatures. Whether from a lack of maintenance or an internal mechanical problem, if your furnace is operating but blowing cold air, it can cause quite an interruption in your daily routine and lead to other problems throughout our home.

If this is something you're currently dealing with, it may having you asking, "Why is my furnace blowing cold air?" And "How can I stop my furnace blowing cold air?" To repair this furnace problem and get back to enjoying a comfortable interior during the heating season, stick around as the furnace technician team from Francis Home Environment clarifies this issue below!

How do you fix a furnace that blows cold air?

Before calling a repair technician to look over your furnace and conduct a furnace repair, there are a couple of troubleshooting steps you can go through that may help fix the problem. Here’s what you can do:

1. Check your thermostat

Confirm that the thermostat settings are programmed to the appropriate temperature. Make sure the furnace fan is on or in the "cool" mode before switching to the heating mode.

2. Inspect the circuit breaker

Make sure your heating system circuit breaker is not tripped. It it has, your electric furnace will have no power to it, and therefore, not be able to generate hot air to distribute through your home.

3. Check the natural gas line and valve

If you have a natural gas furnace, check to see if the gas line is feeding enough gas to your heater. You can confirm this by ensuring the gas valve is turned to the "on" position. If the furnace is not getting enough gas, the pilot light assembly will not be able to start the heating process, which could be the reason why your furnace is blowing cold air instead of heated air.

If the event that the gas is going to your furnace, there may be a gas leak or damage to the gas supply line. In this case, you will need to call a gas company for assistance right away. Leaks in the gas supply can be lethal. As such, if you smell rotten eggs in your home turn off your gas furnace and evacuate your home. Then call emergency services for help.

4. Check your home for any closed supply vents

If there is nothing wrong with the power supply to your furnace, you can then make sure every vent in your house is clear and open. Insufficient air can be the result of closed vents, much like a clogged furnace filter. As such, open any closed vents and ensure there is nothing blocking all the hot air from reaching your rooms.

5. Check the air filter

Check the air filter in your furnace. A dirty air filter can prevent the warm air from moving from the furnace's heat exchanger into the air ducts, leading to your heater blowing cold air instead of warm air. Therefore, we suggest changing out the dirty air filter to see if this can fix the issue.

6. Conduct a system reset

Turn your furnace off and wait a couple of minutes before turning it back on and staring the heating cycle again.

If these troubleshooting tasks don’t fix the problem, reach out to a professional HVAC specialist in your area to schedule a repair appointment.

Should I turn my furnace off if it's blowing cold air?

Yes, you should turn off your furnace until the problem is fixed if it is releasing cold air when it is supposed to be generating heat. Let’s take a closer look at why:

Safety risks

Using a broken furnace longer than necessary can be dangerous. Possible dangers can arise from problems like an electrical breakdown or a gas furnace that does not ignite properly.

Prevent additional damage

By turning off the furnace, you can avoid any potential damage that can arise from the system continuing to function improperly. Additionally, it keeps current problems from getting worse.

Energy efficiency

When a furnace is blowing cold air, it is not using its energy efficiently, and this could result in wasting energy without having the desired heating effect.

Preventing needless expenses

If a broken furnace is left on, it can require more complicated and expensive repairs. By turning it off, you can get help from a professional before more harm is done.

After turning off the furnace, seek advice from a skilled HVAC technician to identify and resolve the issue. Without the required knowledge, attempting to fix complicated furnace problems may result in more problems or safety risks.  

Why is my furnace running, but no heat? 

If your furnace is operating but not generating heat, there are a number of possible causes for this problem. These are some of the common reasons in more detail below:

 Thermostat malfunction

The furnace may not be able to generate heat if the thermostat is not working correctly, has dead batteries, or is set incorrectly.

Clogged air filter

When airflow is restricted by a dirty or clogged air filter, the furnace can overheat and shut off the burners.

Gas supply pipe issues, burnt out pilot lights, or faulty flame sensor malfunctions

Problems with the gas supply, ignition system, flame sensor, or pilot light can prevent your furnace from generating heat. 

Blower motor problems

A faulty blower motor can prevent warm air from travelling throughout your home.

Limit switch problems in modern furnaces

The limit switch kicks in when the furnace overheats to prevent safety features. An ineffective limit switch could force the furnace to turn off before it should, disrupting the appropriate heating cycle.

Gas furnaces experiencing an inadequate gas supply

There might not be enough heat if the gas valve isn't operating correctly, preventing gas from getting to the burners.

Blocked air ducts

The movement of hot air may be impeded by obstructions in the ducting, which will keep it from entering your living areas.

Electrical problems like a tripped circuit breaker

A tripped circuit breaker could disable the furnace's power supply.

Why is cold air coming out of my furnace when the AC is on? Should I be worried?

When your air conditioner is running and cold air is exiting your furnace, there may be a problem with your HVAC system, such as the following:

  • Make sure the thermostat is in the cooling mode by checking it. Cold air may be blasted by the system due to incorrect settings.
  • Warm and cold air may mix in the air due to inefficient cooling caused by dirty or clogged evaporator coils.
  • Inadequate cooling may arise from low refrigerant levels or a refrigerant leak affecting the cooling capability of your air conditioner. 
  • Mixed air temperatures could result from an inaccurately controlled heating and cooling cycle caused by a defective thermostat.

It's best to take immediate action if the furnace is producing cold air while the air conditioner is running. Some causes might be easy to fix, but others might need more comprehensive repairs. It is advised that you speak with a certified HVAC technician if you are unsure how to troubleshoot or solve the issue. Ignoring this problem could result in higher energy usage and less effective cooling, in turn leading to an uncomfortable indoor environment. 

Does your furnace blow cold air? Book a Furnace Repair with Francis Home Environment Today!

For any and all furnace problems you may be experiencing, the team at Francis Home Environment is your go-to for high-quality repair solutions!

Francis Home Environment proudly operates throughout Ottawa, Greely, Arnprior, Vanier, Stittsville, Rockland, Carleton Place, Kanata, Almonte, Russell, Orleans, And Kemptville. Understand that furnace issues can arise at any time, which is why our certified HVAC technicians are available 24/7/365 days a year, including after-hours, weekends, and holidays, at no extra cost. We are also available for same-day repairs in case you experience a heating emergency in your home during the middle of winter.

Give the Francis Home Environment team a call directly or use our online booking form to reserve your repair appointment today.