Furnace Short Cycling Issues

Furnace short cycling refers to the switch-on and switch-off of a furnace system without reaching the set temperature on the thermostat. Short cycling causes your home not to be as warm as it should, leaving you and your loved ones uncomfortable.

Here are the common causes of furnace short cycling problems:

Furnace Short Cycling 1: The Thermostat is Not Set Up Correctly

The most common cause of furnace short cycling is not setting up the thermostat correctly. It is essential to choose the correct setting, whether it is heat or cool.

The following are the symptoms of this problem:

Furnace frequently tries to heat even when the thermostat is 60 degrees. The thermostat continues to change its temperature setting after it has reached the desired temperature. The thermostat tries to heat when it is set to cool.

Furnace Short Cycling 2: The Thermostat is Not Communicating Properly

A furnace should operate automatically without glitches if it has a working thermostat. If your thermostat is not connecting correctly to the furnace, it will likely change the temperature setting without getting the desired results.

It may be due to one of the following problems:

  • There is a loose connection between the thermostat and the furnace.
  • There is a loose wire connection with the thermostat.
  • There is a faulty thermostat.

If none of the above situations apply, you might need to change the thermostat.

Furnace Short Cycling 3: Dirty Air Filters

A dirty air filter can cause the furnace to short cycle, leaving your home not as warm as it should be.

The main reason behind this problem is that the dirty air filter takes longer to heat up, resulting in the furnace shutting down too early.

Furnace Short Cycling 4: Faulty Blower Motor

If the blower motor is not working correctly, it must be replaced. In addition to this, if the air filter is not arranged correctly, then it must be replaced.

Furnace Short Cycling 5: Low Refrigerant Level

One of the most common causes for short cycling is low refrigerant. If the refrigerant level is low, the heat pump cannot perform to its fullest capacity. If you notice any of the following symptoms, there is likely a leak in the system.

In the case of a heat pump, you can notice that the blower is not working properly. It is essential to have your heating system checked by heating specialists if you feel a problem with your furnace.

Furnace Short Cycling 6: Failed Thermostat

In some cases, if it is not your fault, then the problem may be with the thermostat. It may have failed to sense the temperature.

Though it is rare, it is still essential to understand if this is the case. If you feel that the thermostat is not giving the right temperature setting, you need to replace it.


If you notice that your furnace system is short cycling and not giving the right temperature, you may want to address the problem as soon as possible.

If the problem is because of dirty filters, then you will want to replace them as soon as possible. If it is because of low refrigerant, you need to have it checked by a professional. If you feel that there may be a problem with your thermostat, you need to replace it.

Legacy Heating specializes 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! If you need furnace repair services in Edmonton, AB, get in touch with us! Call us at 780-900-2942 for immediate assistance. 

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