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Furnace Blowing Cold Air

Furnace fan runs but blows cold air. Thermostat checks, safety, and the parts a technician tests.

Safety first. If you smell gas (a rotten egg smell) or hear hissing near a gas appliance, leave the building now. Do not use light switches, phones or anything that can spark inside. From a safe place, call 911 and your gas company (Enbridge Gas Utah emergency line: 1-800-767-1689). (Source: Enbridge Gas) If a carbon monoxide alarm sounds or people feel headache, dizziness, nausea or confusion, get everyone outside to fresh air and call 911. (Source: U.S. Centers for Disease Control and Prevention; U.S. Environmental Protection Agency) Do not try to repair gas, refrigerant or electrical parts yourself.

Safe things to check

Check that the thermostat fan is set to Auto, not On. With On, the fan runs between heating cycles and the air feels cool.
Check the air filter. ENERGY STAR says to check the air filter every month, change it if it looks dirty, and change it at least every 3 months. A dirty filter slows airflow, makes the system work harder and can lead to early failure. (Source: ENERGY STAR (U.S. EPA))

Stop here

Do not open the burner compartment or touch the gas valve. If you smell gas, leave and call 911 and your gas company from outside. (Source: Enbridge Gas)

What a technician checks

A technician checks ignition (ignitor and flame sensor), the draft inducer motor, and safety switches. Angi lists draft inducer motor repair or replacement at $200 to $1,500. (Source: Angi)

Typical cost

Angi: ignitor $150 to $250; flame sensor $150 to $250; draft inducer motor $200 to $1,500. (Source: Angi) National figures; not a quote.

Need a technician? Send a request to Refrigerate.
Refrigerate LLC in Lindon has HVAC-certified technicians and reviews every request. Prefer to talk? Call or text (801) 899-2171.

Refrigerate runs this site. Not for emergencies: for a gas smell or CO alarm, leave and call 911.

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FAQ

Can I fix this myself?

Only the simple checks listed above. Gas, refrigerant and electrical work needs a trained HVAC technician.

Can this site tell me what is wrong with my furnace or AC?

No. Utah HVAC Help is general information, not a diagnosis. Gas, refrigerant and high-voltage electrical parts need a trained HVAC technician. If you smell gas or a CO alarm sounds, leave the building and call 911 and your gas company from outside.

Sources

Report Gas Emergency (Utah, Idaho and Wyoming), Enbridge Gas
Heat and Cool Efficiently, ENERGY STAR (U.S. EPA)
How Much Does the Average Furnace Repair Cost? (2026 data, updated Sep 25, 2026), Angi

Last checked October 27, 2026. Prices and rules change; confirm with the source before you rely on them.