5 Furnace Troubleshooting Tips To Try Before Getting Help

As a homeowner, knowing a few furnace troubleshooting tips can help you when the system stops working. These could save you the discomfort you could experience waiting for an HVAC technician to repair it. Most of the time furnaces operate seamlessly, but issues with the thermostat, gas supply or electrical components can interfere with its operation.


  • Check the thermostat. The thermostat controls when yourfurnace turns on and off. If it’s malfunctioning or set to “off” or “cool,” that could be your problem. It could also be set too low. Listen for a click and shortly thereafter, the gas entering the burner.
  • Look at the air filter for the furnace. Some have switches that shut the furnace off if there’s inadequate airflow through the system. You’ll increase the life of your furnace by keeping the filter clean.
  • Check the power supply. Look inside the circuit breaker box and verify that the circuit breaker hasn’t tripped. If it has, turn it off completely, and then turn it back on. You can also check the switch inside the furnace, which may be a switch or a button. Push or trip it. Most of the time a furnace won’t shut itself down. If this happens again shortly after turning the furnace on, contact an HVAC contractor to handle this aspect of furnace troubleshooting, and turn the system off.
  • Check the gas valve. Verify that the gas valve to the furnace or your home is on.
  • Inspect the pilot if your furnace uses one. Furnaces have a thermocouple that will shut the gas supply off when the pilot stops burning. The pilot or thermocouple may be dirty or need replacing. If you’re an experienced do-it-yourselfer, you may be able to clean it. If you’re uncertain, let a pro do it for you. If your system is pilotless, the flame sensor may be dirty. If you’re confident of your ability, you may be able to clean it. Both the thermocouple and flame sensor are critical safety features.


To learn more about furnace troubleshooting and avoid problems with its operation, contact Keith Air Conditioning, providing HVAC services for Baldwin County homeowners since 1964.

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