Furnace Blowing Cold Air: Fan or Heating Failure?
If you smell gas or a CO alarm sounds, leave the home and call the gas utility or 911 from outside.
A furnace blowing cold air may be moving air without producing heat. Check whether the thermostat fan setting is ON rather than AUTO, then confirm the heating mode and room temperature. If cool airflow continues during a heat request, the furnace needs diagnosis rather than repeated thermostat changes.
Talk to a contractor about your furnace blowing cold air
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 Not Blowing Hot Air? Get Help Now - Trane:
The problem: The fan is set to On instead of Auto.
Discuss your furnace blowing cold air 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
Write down whether the air is cool only between heat cycles or stays cool throughout a call for heat. Check an accessible filter with the system off.
Details to give the contractor
Tell the contractor whether the burners ever appear to light through the normal viewing window. Include any status code already visible without opening the cabinet.
Gas smell and carbon monoxide alarms
According to CPSC Carbon Monoxide Fact Sheet:
Immediately move outside to fresh air.
Related symptoms and code references
What happens when you call about your furnace blowing cold air
- 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 Not Blowing Hot Air? Get Help Now - Trane · Read 2026-11-01
- CPSC Carbon Monoxide Fact Sheet · Read 2026-11-01