Why is my gas furnace blowing cold air when the heat is on?

Possible causes include fan settings, startup timing, restricted airflow, ignition problems, or a protective shutdown. Persistent cold airflow requires diagnosis.

Why does my furnace blow warm air and then cold air?

This can happen between normal heating cycles, especially with the fan set to On. It can also happen when burner operation stops unexpectedly. Whether the home reaches the thermostat setting helps distinguish the situations.

Can a dirty filter make a furnace blow cold air?

Restricted airflow can contribute to overheating and a protective shutdown. The blower may continue running after the burners stop. Follow the manufacturer's filter guidance and arrange service if the problem continues.

Does cold air mean the furnace needs replacement?

No. Cold airflow is a symptom. Replacement should be based on diagnosed faults, equipment condition, safety, and the practicality of repair.

Should I change the thermostat fan from On to Auto?

If you want the fan to follow the normal heating sequence, Auto may be appropriate for your system. Check the equipment instructions. A fan-setting change will not correct an underlying heating fault.

Can a faulty ignitor cause a furnace to blow cold air?

An ignition failure can prevent the burners from producing heat. Whether the blower operates during that condition depends on the equipment and controls. Testing is needed to identify the cause.

Should I keep restarting a furnace that blows cold air?

Avoid repeated resets when the furnace keeps shutting down. A recurring fault needs investigation, particularly if a safety control is interrupting operation.

Does NexPro repair gas furnaces in Newton, MA?

NexPro provides heating repair and diagnostic services in Newton and nearby communities. Contact the team to confirm availability, appointment details, and the diagnostic fee.

Gas Furnace Blowing Cold Air? Causes & Repair Options

HVAC & PlumbingNewton & Greater Boston

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