Furnace Wont Stop Running: Heat or Fan?
If you smell gas or a CO alarm sounds, leave the home and call the gas utility or 911 from outside.
A furnace that will not stop running may have a continuously selected fan or a heating-control problem. First distinguish airflow from active heat, and compare the room reading with the setpoint. If heating continues after the thermostat no longer requests it, stop troubleshooting and arrange a professional control-system diagnosis.
Talk to a contractor about your furnace won't stop running
Call (877) 565-3062One call reaches a contractor registered for your ZIP; ask the fee and the arrival window.
HVAC Responder Editorial Team · Reviewed 2026-11-01 · Facts quoted from manufacturer documentation
What the source supports
According to Furnace Won't Shut Off - Troubleshooting Tips - Trane:
Problem 1: Incorrect thermostat settings The most common reason for a furnace fan that won’t shut off or a furnace blowing cold air and won’t shut off is the wrong thermostat settings.
Discuss your furnace won't stop running with a contractor
Call (877) 565-3062One call reaches a contractor registered for your ZIP; ask the fee and the arrival window.
Safe observations before the service call
Look at the fan setting and the displayed heating request. Do not disconnect thermostat wires to force a shutdown or open a live control compartment.
Details to give the contractor
Explain whether only air movement continues or the home keeps getting hotter. Record the thermostat mode, setpoint, and actual room temperature at the same time.
Gas smell and carbon monoxide alarms
According to CPSC Carbon Monoxide Fact Sheet:
Immediately move outside to fresh air.
Related symptoms and code references
- Furnace Not Turning On: Checks Before Calling
- Furnace Blowing Cold Air: Fan or Heating Failure?
- Furnace Short Cycling: Repeated Starts and Stops
- Carrier furnace codes
- Goodman furnace codes
- Lennox furnace codes
- Rheem furnace codes
- Trane furnace codes
- York furnace codes
- Furnace cold-air guide
- All HVAC problem pages
What happens when you call about your furnace won't stop running
- Your call routes to an independent local contractor registered for your ZIP code.
- Ask the fee and the arrival window.
- The decision to hire stays with you.
One call reaches a contractor registered for your ZIP; ask the fee and the arrival window.
Sources and review date
- Furnace Won't Shut Off - Troubleshooting Tips - Trane · Read 2026-11-01
- CPSC Carbon Monoxide Fact Sheet · Read 2026-11-01