Troubleshooting Guide to Common Furnace Problems – Sobieski Services | DE, NJ, PA, MD

Troubleshooting Guide to Common Furnace Problems


If you’ve used furnaces for home heating for years or even decades, problems may still arise that you’re unfamiliar with – especially with today’s high-tech systems. While professional HVAC maintenance is the best option to prevent furnace problems, try the following troubleshooting tips if your system conks out when you need it most.

Zero Heat Output

  • Make sure the thermostat is in “heat” mode and set below room temperature.
  • Check the circuit breaker or fuse box for a tripped breaker or blown fuse.
  • If you’re starting your furnace for the first time this season, the gas valve may be off.

Poor Heat Output

  • A dirty or clogged air filter may substantially reduce airflow. Change the filter as needed.
  • If the gas burner flame is not a sharp blue color, the burner needs to be cleaned.
  • There may be an obstruction to the combustion air chamber or direct-venting intake.

Short Cycling

Is your furnace cycling on and off too frequently? There could be a problem or setting error with the heat anticipator in the thermostat. Adjust the metal pointer on the back of the thermostat one or two notches, or refer to your thermostat owner’s manual.

Noisy Operation

Take unusual noises seriously to avoid a major malfunction. If you hear a grinding noise, turn off the furnace and call your HVAC provider. You may have a failing blower motor. Squealing sounds indicate a loose or worn belt. A low-pitched rumbling indicates dirty gas burners.

Blower Runs Continuously

  • Check to make sure the thermostat is not in “fan” mode, which calls for continuous blower operation regardless if heating is activated.
  • A faulty fan limit control switch causes the blower to run continuously when there is no “fan” mode on the thermostat.

If you’re still having furnace problems following these troubleshooting tips, please contact Sobieski Services, Inc. for assistance.

At Sobieski Services, Inc., our goal is to help our customers in Delaware, Pennsylvania, Maryland and New Jersey learn more about energy and home comfort issues – especially HVAC and plumbing issues – so that they can save money and live in healthier, more comfortable homes.

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