A furnace is essential for keeping your home warm during Saskatoon’s harsh winters. But what happens when your furnace starts blowing cold air instead of heat? This can be frustrating and uncomfortable, especially when temperatures drop. Let’s explore the possible reasons why your furnace is not functioning properly and what you can do about it.
Your Thermostat Settings May Be Incorrect
Before assuming the worst, check your thermostat settings. Ensure it is set to “heat” rather than “cool” or “fan.” If the fan is set to “on,” it will blow air continuously—even when the furnace isn’t heating. Switching the fan setting to “auto” will ensure warm air is only circulated when needed.
The Furnace Filter is Dirty or Clogged
A dirty air filter can block airflow, causing the furnace to overheat and shut down the burners as a safety measure. While the blower may continue running, it will only push out cold air. Replacing your furnace filter regularly—typically every 1-3 months—can prevent this issue and improve efficiency.
Pilot Light or Ignition Issues
If you have an older furnace with a pilot light, check if it has gone out. If so, relight it according to the manufacturer’s instructions. Newer furnaces use electronic ignition, which can fail due to a faulty sensor or ignition system. If you suspect an ignition problem, it’s best to call a professional for repair.
Clogged or Leaky Ductwork
Air ducts distribute heated air throughout your home. If there are leaks, blockages, or significant dirt buildup in the ductwork, warm air may not reach its destination, leaving only cool air blowing through the vents. A professional duct inspection can identify and fix these issues.
Furnace Overheating and Shutting Down
If your furnace is overheating, it will shut down as a safety precaution. Overheating can occur due to restricted airflow, a malfunctioning blower motor, or a dirty heat exchanger. A licensed HVAC technician can diagnose the problem and restore proper function.
A Faulty Limit Switch
The limit switch controls the operation of the blower. If it malfunctions, the furnace may keep running even after the burners have turned off, leading to cool air blowing through the vents. A professional should inspect and replace the switch if necessary.
Low Gas Supply or Gas Valve Issues
A furnace that isn’t receiving enough gas may fail to produce heat. Check other gas appliances in your home to see if they are functioning. If you suspect a gas supply issue, contact your gas provider or an HVAC technician for further assistance.
What Should You Do If Your Furnace Blows Cold Air?
If your furnace is blowing cold air, follow these steps:
- Check your thermostat settings to ensure it’s on “heat” and “auto.”
- Inspect the air filter and replace it if it’s dirty.
- Look for a pilot light issue if you have an older furnace.
- Check your ductwork for leaks or blockages.
- Call a professional HVAC technician if the issue persists.
Preventative Maintenance for a Warm and Efficient Home
Routine furnace maintenance can prevent many of these issues. Scheduling an annual inspection with Pro Service Mechanical ensures your furnace is running efficiently and reliably throughout the winter. Regular tune-ups help detect potential problems before they become costly repairs.