Signs Your Furnace May Need Professional Attention

Michigan winters put serious demands on residential and commercial furnaces. Over 38 years in the HVAC industry, we have seen that most heating breakdowns give early warning signals before they shut down completely.

1. Unusual Noises During Operation While mild airflow whooshing is normal, distinct squealing, rattling, or metal-on-metal banging indicates mechanical distress. A high-pitched squeal often points to a worn blower belt or dry motor bearings. Banging or popping when the furnace ignites could indicate delayed ignition, where gas accumulates briefly before igniting.

2. Yellow or Flickering Burner Flame A properly operating natural gas furnace should burn with a steady, crisp blue flame. A yellow, dancing, or wavy flame suggests incomplete combustion. This can occur when burners are dirty, oxygen intake is restricted, or the heat exchanger has developed issues. If you notice a yellow burner flame, contact an HVAC professional promptly.

3. Frequent Short Cycling When a furnace kicks on, runs for only two or three minutes, and shuts down before the home reaches the thermostat temperature, it is "short cycling." Common culprits include dirty air filters restricting airflow, an overheating heat exchanger tripping the high-limit switch, or a failing flame sensor.

4. Cold or Lukewarm Air From Supply Registers If your furnace blower runs constantly but the air coming through your registers feels lukewarm or cool, check the thermostat fan switch first (set it to AUTO rather than ON). If the fan is set properly, the issue may involve the pilot assembly, electronic ignition control, or limit switch.

5. Unexplained Spike in Heating Bills If your gas or electric bills rise significantly without a change in outdoor weather or thermostat habits, your furnace is likely working harder and running longer cycles due to component wear or restricted airflow.

Regular evaluation by an experienced technician ensures your system operates safely, reliably, and efficiently throughout the Metro Detroit winter.