Why Is My Furnace Blowing Out Cold Air?

April 16, 2021

furnace blowing out cold air

We are trusted for 24/7 furnace repair in the Denver area. One of the problems customers often face is a furnace that blows out cold air, and this is not something you want in the middle of a Colorado winter. There are many reasons for this to happen. Some of the causes our technicians look for during furnace troubleshooting include:

Empty Oil Tank

When an oil-fired furnace runs out of fuel, it cannot provide heating. However, the blower will still continue to run. It will circulate cold air long after the burners fail to ignite. Fortunately, if there are no other problems, refueling the furnace will restore your supply of warm air.

Overheated Furnace

Overheating is often caused by a lack of airflow brought on by a clogged air filter. If your furnace overheats, the burner will shut down, preventing the system from producing hot air. Changing the air filter should resolve the issue.

Pilot Light is Out

Fuel combustion cannot occur if the pilot light goes out. To relight it, turn off power to the appliance, turn off the pilot light reset switch, and wait 10 to 15 minutes. This allows any gas that has escaped to ventilate. Then turn the reset switch to PILOT and light outgoing gas with a lighter or match at the pilot end. When the pilot light is lit, flip the switch to the ON position and restore power to the unit.

If the pilot light does not relight or keeps burning out, contact a local heating repair professional.

Dirty Air Filter

A furnace relies on the movement of air to function properly. A dirty filter can both restrict airflow and cause the unit to heat up. Dirty air filters must be replaced to prevent major damage. If your furnace has a filter access door, remove it, and then slide out the old filter and dispose of it. Make sure the new filter has the same dimensions and insert it, paying careful attention to the directional markings on the filter frame. Once the access door is replaced and the furnace cools down, it should restart.

Broken Control Panel

When you’re only getting cold air, the electronic control panel may have malfunctioned. Resetting the system can help determine if this is the case. To do so, turn off the furnace power switch and, after a few minutes, turn it back on. If rebooting your furnace doesn’t resolve the problem, call a repair technician.

Leaking Ducts

The hot air produced by your furnace may be escaping through gaps, holes, and tears in your ductwork. Your HVAC vents will therefore blow cold air. If other remedies don’t fix the problem, then have an HVAC technician perform an inspection of your air ducts.

Valve Issue

A gas valve problem can prevent the pilot light from going on. Dirt can cause a valve to get stuck, especially if the furnace hasn’t been cleaned recently. It’s best to call a professional to thoroughly clean or, if necessary, replace the faulty valve.

Wrong Thermostat Setting

People often disagree with one another about the best thermostat setting. If your furnace is blowing cold air, one reason may be the thermostat was turned off. Perhaps they set it from AUTO to ON, which causes the fan to run continuously without the unit supplying heat. To restore heating, turn the thermostat switch back to AUTO.

If there’s a problem with the thermostat, it might not send the right signal to the furnace. Replace the temperature control system if this is the case, or upgrade to a programmable or smart thermostat for improved comfort control and energy efficiency.

Faulty Flame Sensor

Your furnace starts to blow warm air. However, this quickly cools off. The flame sensor may be dirty or worn out. To get the burner going again, clean the sensor or have an HVAC professional replace it. Our technicians have the furnace repair parts to get your heating system running again quickly.

Contact Fix-It 24/7 for Furnace Repair in Golden, CO

Fix-It 24/7 provides heating, AC, plumbing, and electrical repair service throughout the Denver area. Family-owned and operated, we are committed to providing world-class customer service whether you need repairs, maintenance, or a new installation. If your furnace is blowing cold air, call 720-927-9357 or fill out our online form to request a service visit.

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