Goodman furnace short cycling in Toronto, ON

Furnace Turns Off and On Repeatedly

Many of us have furnace problems, particularly during cold periods. We often wonder why our furnace turns off and on repeatedly (or short cycling). Many people are confused about short cycling.

How can I tell if my Furnace is short cycling? 

Short cycling is easy to identify as the furnace will turn on and off repeatedly in a short time. It can turn off and on for approximately two to three minutes.

On the other hand, the furnace switches on and off several times per hour, often lasting five to fifteen minutes. The furnace will reach the desired temperature quickly.

It takes various factors to get a house to the right temperature. These factors include the size of the home, outside temperature, insulation and furnace type. For instance, if you live in an older house with poor insulation, the furnace will work harder to maintain temperature.

Short Cycling Furnace

Here are some causes why your furnace is turning on and off repeatedly. 

Overheating furnace 

The furnace’s performance will be affected by the age of your furnace. Older furnaces heat up more than newer furnaces.

Furnaces can overheat when there is insufficient airflow. Your furnace may become damaged if you use it too often.


Let’s say your furnace is heating up at home. You should inspect and maintain the furnace filter. It would be best if you cleaned the filters and your furnace. Dust and other debris build up in your furnace. The dust buildup restricts airflow, making it difficult for the furnace to maintain proper air circulation.

Dirty furnace filters You should change or upgrade your furnace’s air filters to improve indoor air quality.

Flame sensor 

Often, a faulty flame sensor can cause short cycling. The furnace flame sensor measures the gas entering your furnace.


The flame sensor will lose its ability to detect the correct amount of gas entering the furnace if clogged with dirt. A clogged flame sensor can cause problems with safety features such as the gas valve that is supposed to shut off the gas supply to prevent excessive gas buildup.


It is essential to clean the flame sensor and schedule a furnace tune-up regularly.

The Furnace Blower Motor is not Working

Short cycling can occur if the blower motor stops working.

Your furnace’s blower motor is responsible for blowing heat through your heat exchanger. Imagine that your furnace’s blower motor has stopped working. If this happens, heat buildup in the furnace will cause some safety features, such as the high limit furnace switch.

It is essential to regularly check your furnace’s blower motor and the vent system. 

An Incorrect Size Furnace

A poorly sized furnace can be a significant problem when replacing your furnace. It will shut off and turn on again. An oversized furnace will consume a lot of energy. Because the furnace heats up quickly, switching on and off will be more frequent.

After the furnace has warmed up your home quickly, it will turn off. The furnace will turn itself back on if the temperature inside drops—this cycle repeats, overusing your furnace.

The Thermostat Isn’t Working 

If not adequately maintained, thermostats can malfunction in some cases. If your residential thermostat does not work correctly, The furnace is displaying false readings, which will cause it to turn off and on again.

Check the thermostat batteries to ensure that they are appropriately charged. Adjust the thermostat to your desired temperature.

Maintain Your Furnace 

You know what to do if your heating system is causing it to turn off and on more often than it should. Proper cleaning and maintenance are essential to ensure that your furnace is efficient and lasts a long time.

Summary – Furnace Turns Off and On Repeatedly

Suppose you don’t know how to fix a specific furnace problem. If that is the case, you can call your trusted HVAC technician to resolve the furnace problem.