HVAC TROUBLESHOOTING GUIDE

Furnace Blowing Cold Air: What Could Be Wrong?

Brief cool airflow can occur at startup or shutdown, but continuous cold air during a heat call points to a problem.

Call to request heating or cooling service in Littleton.

START HERE

Safe checks before scheduling service

Confirm the thermostat is in HEAT rather than FAN-only mode.
Check whether the furnace appears to ignite and then shut down.
Replace a severely dirty filter.
Note any blinking diagnostic code visible without opening the equipment.
If you smell gas, leave the area and follow your gas utility's emergency guidance.

If you encounter exposed wiring, smoke, a gas odor, a carbon-monoxide alarm, or another immediate safety concern, stop troubleshooting and follow the appropriate emergency guidance.

WHEN TO CALL

Move from troubleshooting to diagnosis

If the simple checks above do not resolve the problem, or the same symptom returns, professional diagnosis is usually more useful than continuing to reset or restart the equipment. Describe the symptom and what you have already checked.

WHAT NOT TO DO

Avoid risky shortcuts

Do not bypass switches, defeat safeties, open sealed refrigerant systems, adjust gas valves, or repeatedly reset a breaker that trips. Those steps can create additional risk or obscure the original problem.

LOCAL HVAC HELP

Still having trouble? Call for local HVAC help

Tell us what your heating or cooling system is doing and request service in Littleton.

Call 303-632-9562

RELATED HVAC HELP

Furnace Blowing Cold Air: What Could Be Wrong?

Safe checks before scheduling service

Move from troubleshooting to diagnosis

Avoid risky shortcuts

Still having trouble? Call for local HVAC help

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