The Most Common Reasons Your Furnace Is Freezing Up

Your furnace may be frozen due to a number of reasons. One common reason is that the furnace is not getting enough airflow. This can be caused by several things, such as a clogged air filter or a blockage in the venting system. If you think that your furnace may be frozen, it is crucial to call a professional to have it checked out. Find out what may be causing your furnace to freeze up by reading the reasons below:

Blocked Airflow

To keep your HVAC system working properly, you need to ensure that air flows freely throughout the entire system. If the air passages become restricted, it can cause the system to stop working correctly. This can be caused by factors such as sagging ventilation pipes or items in the exhaust vent. 

Ice can form around the vents when this happens, causing the unit to freeze. To prevent this, you should check the vents and pipes regularly to ensure they are clear. You can also get a vent screen to prevent anything from entering the exterior vent.

Coolant Leaks

The coolant in an HVAC system keeps the air temperature regulated. If the coolant levels are low, the system will not function properly, and the air will not blow correctly. This is an issue that needs to be fixed by a contractor. In the meantime, people can put a sealant on the area where the coolant is dripping, but this does not solve the underlying problem. 

The contractor will need to identify the root cause of the issue, which is often coils that need to be replaced. This is a fixable problem, but it is vital to address it in a way that will prevent it from happening again in the future.

Dirty Coils

The evaporator coils are responsible for converting the air into heat. It is essential to keep these coils clean, as dirt and debris can build up and restrict airflow. Additionally, ice can form and freeze the system. Though you can perform minor clean up on your own, more extreme issues require a Legacy Heating and Cooling HVAC technician.

Faulty Thermostat

There may be an issue with the thermostat or room sensors that is causing your HVAC system to work overtime. The controls on your HVAC system manage the heating, cooling, and humidity levels in the room. If the thermostat is not working properly, it can cause the air conditioner to run constantly, even when the temperature is low.

The sensors in your room may not be accurate, which could cause your HVAC to run constantly. If the AC constantly runs, the coils could freeze and shut down the system.


If your furnace is freezing up, you can do a few things to try and fix the problem. First, check to see if the air filter is clean. If it is dirty, replace it with a new one. Next, check the blower motor to see if it is working correctly. If it is not, you may need to replace it. Finally, check the ductwork to see if there are any leaks. If there are, you will need to have them repaired. Always trust only the professionals at Legacy to deal with your furnace. 

Are you looking for a new furnace in Calgary and Edmonton? Turn to Legacy Heating. We specialize in HVAC systems for residential new home construction (RNC) and installing and replacing furnaces, air conditioners, air cleaners, thermostats, humidifiers, heat recovery ventilation (HRV) units, humidifiers, and unit heaters, as well as other HVAC products! Get a free quote today.

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