Why is My Furnace Not Blowing Hot Air?

Nobody wants to come home to a cold house, especially when it’s cold and blustery outside. So, if you come home on a cool day and your furnace is blowing cold air, it’s time to troubleshoot. Here are some tips to help you figure out why your furnace is not blowing hot air before carrying out some furnace maintenance.

A Problematic Thermostat

A lot of things can go wrong with your thermostat. So, it’s one of the best places to start your checks.

Fan is Set to On

Furnace thermostats are designed to switch on and off depending on room temperature. When the air gets too cold, they turn on and start blowing warm air until things return to the set room temperature.

However, leaving the fan set to ‘on’ will blow cold air rather than turning it off. You can fix this by switching your fan to auto.

Somebody is Messing with the Thermostat

Some like it hot, some like it cool. We all have our own comfort zone when it comes to the temperature in our homes. But you might be surprised by how much your family members are fiddling with the thermostat. If you live with other people in the household, keep an eye on your thermostat to spot any changes.

Low Battery

When the thermostat battery runs low, the display will dim, and the thermostat will not be able to perform any functions until the battery is replaced. Always contact a furnace technician to unsure how to check or change the battery.

Air Filter is Clogged or Dirty

Dirty or clogged air filters can cause various problems with your heating system. Dirt and dust build up on the filter over time can reduce the amount of air that flows through it. This can cause your furnace to work harder than it should and could be the cause of cold air.

High Limit Switch Failed

A high limit switch is a safety device that protects your HVAC system. It’s designed to turn off power to the furnace or air conditioner if the temperature reaches a certain level. The purpose of this is to prevent overheating and damage to your unit.

If your high limit switch has stopped working, it’s essential to take action quickly and book a furnace maintenance or repair.

Clog in the Condensate Drain Line

The condensate drain line is a tube that runs from the bottom of your furnace down through the floor and into a drain in your basement or crawlspace. The problem comes when this pipe gets clogged with debris or mineral deposits, preventing water from draining out of the unit as intended.

Issues with the Fuel Source

Check the fuel source. If you have an oil-fired furnace, ensure that there is oil in it. If your furnace uses natural gas, ensure that there is gas coming into the house and that the pilot light has been lit. For electrical furnaces, check the fuses.

Broken and Leaking Ducts

The problem could be as simple as loose or disconnected ductwork leaking warm air and  letting cold air in. Some duct repairs you might be able to carry out yourself. But if you’re having trouble, call for professional help and book a furnace tune-up.

Pilot Light Isn’t On

If your pilot light isn’t on, it may not be safe to use your furnace. The pilot light ignites the gas in the furnace, which heats up and circulates through the system to provide heat to your home.

If you notice that there’s no gas coming out of your pilot light, but the switch is still clicking on and off every few seconds (or longer), then there’s probably something wrong with one of two things – either the switch itself has failed, or the gas supply has run out.

Burner Issues

The burner is the part of your furnace that produces heat, so when it gets blocked by dust or other debris, it can’t do its job. When this happens, the fans blow cold air, lowering your home’s temperature. Arrange a furnace tune-up to clean your burner – this should solve the issue and get your home warm again in no time.

Flame Sensor Issues

A dirty or worn flame sensor in your furnace can cause the blower to run constantly, even when the thermostat is calling for heat. The flame sensor is located in front of the burners and detects when a flame is present. Problems occur when dirt and grime can build up, causing the burner to shut off.

Always Call a Professional for Furnace Maintenance

Furnaces are complicated machines, and they’re designed to be safe and efficient. However, they also need maintenance and tune-ups to keep them working properly. Regular furnace maintenance and tune-ups can help prevent damage, extend the life of your furnace and save you money on energy bills.

Keep your furnace in top working condition by booking a furnace tune-up with Bell Bros. Our experts will ensure your home stays warm and cozy this winter.