When your furnace turns on and then switches off after a few minutes, you must determine the problem so that you can keep your house warm throughout the cold winter months. Short cycling is a term used to describe a furnace that repeatedly starts and shuts down.
Short-cycling, or having a furnace switch off and on faster and more frequently than you have planned, is a major issue for homes. It is not simply inconvenient; if the poor heating pattern persists, heating costs can become exorbitantly costly.
Reasons Why Your Furnace Keeps Shutting Off
There are several possible explanations for your furnace’s short cycling; therefore, let us look at the causes and solutions:
1. Dirty or Faulty Flame Sensor
If your furnace shuts off after a few minutes, it is likely because the flame sensor is rusted or caked in soot. This critical component intends to monitor the gas burner. When it becomes rusted or soot-covered, it loses its ability to detect flame — even when the furnace is on.
As a result, the gas valve is turned off. You will not be able to heat your home without gas, and your furnace will continually shut down. This might be a rather simple repair.
2. Insufficient Airflow
When your furnace begins and stops, it might be an indication that you have insufficient airflow. If there is low airflow, the heat exchanger in the furnace may frequently overheat. This problem is more likely to arise if the furnace is in a congested storage space blocking the air inlet into your home from the outside.
When the exchanger reaches its maximum temperature, the furnace automatically shuts off after a few minutes. Resolving the problem of inadequate airflow necessitates a multi-pronged strategy. To begin, ensure that all of your air filters are clean. They should be updated every few months to ease the burden on your HVAC system and to guarantee that filtered air enters your house.
3. Faulty Pressure Switch
The pressure switch closes with airflow from the draft inducer motor through the burner to signal safe ignition. If the switch fails, the ignition is not notified that it is safe to proceed. As a result, the ignition is halted after only a few minutes, and the furnace is turned off. A multimeter can help you determine if the pressure switch is malfunctioning.
4. Broken Draft Inducer Motor
A draft inducer motor’s principal duty is to pull air into the burner and out. It also pulls in enough air to shut the pressure switch and start the burning process. If the draught inducer motor fails, it will not provide the necessary conditions for the pressure switch to close and light the furnace. As a result, the furnace will turn on and then off after a few minutes.