5 Common Furnace Problems and How to Troubleshoot Them

1. Furnace Won't Turn On

Check the thermostat. Ensure it's set to HEAT and the temperature is set higher than room temperature. Replace batteries if applicable.

Check the power. Verify the furnace switch (usually near the unit) is ON. Check circuit breakers.

Check the gas valve. Make sure the gas supply valve is open.

If these don't help, call a professional - there may be an ignition or safety switch issue.

2. Furnace Runs But No Heat

Check the filter. A severely clogged filter can restrict airflow to the point where safety switches shut off the burners.

Check vents. Ensure supply and return vents are open and unobstructed.

Listen for ignition. If you don't hear the burners light, there may be an ignition problem.

3. Furnace Short Cycling

Short cycling (turning on and off frequently) often indicates a dirty filter, oversized unit, or malfunctioning flame sensor. Replace the filter first.

4. Strange Noises

Banging at startup could indicate delayed ignition - a potentially dangerous condition. Squealing might mean belt or bearing issues. Both warrant professional attention.

5. Uneven Heating

If some rooms are cold while others are warm, check for closed vents, dirty filters, or duct problems. Balancing issues may require professional adjustment.

When to Call a Pro

For gas-related issues, strange smells, or problems beyond basic troubleshooting, contact a licensed technician. Safety first.