Why Is My Furnace Blowing Cold Air?

Your furnace has a blower that moves air through the house and a separate part that produces heat. When the heating stops but the blower keeps running, cold air comes through your vents.

A thermostat setting, dirty filter, or failed furnace part can cause this. Before calling Blake Brothers, check your thermostat and filter. Leave anything involving gas, wiring, or internal repairs to a technician.

Check Your Thermostat First

Look at the fan setting. ON keeps air moving even when your furnace isn't heating. Switch it to AUTO.

Check the other settings:

• Make sure HEAT is selected.
• Set the temperature above the room reading.
• Check your programmed schedule for changes.

Give your furnace a few minutes to warm up.

Check the Furnace Filter

Pull out your filter if you can reach it safely. If it's packed with dust, replace it with the correct size and type.

A clogged filter blocks airflow and can cause your furnace to overheat. If the furnace continues shutting down after you've changed the filter, turn it off and arrange a repair.

Common Reasons a Furnace Blows Cold Air

Once you've checked the basics, the trouble may be inside your furnace.

Thermostat or Fan Setting

A faulty thermostat or damaged wiring can keep your furnace from receiving the signal to heat, even with the correct settings.

Restricted Airflow

Blocked vents or damaged ducts can restrict airflow. Make sure furniture isn't covering your vents.

Ignition or Burner Problem

Your gas furnace needs its burners to light before it produces heat. A failed igniter or gas control can prevent that. Leave these repairs to a technician.

Furnace Overheating or Safety Shutdown

If your furnace gets too hot, a safety switch shuts off the heat. The blower may continue running to cool the equipment.

Blower, Electrical or Control Problem

A failing blower motor can leave you with weak airflow. Electrical problems can interrupt heating or keep the furnace from starting.

Why Does My Furnace Start Warm and Then Blow Cold Air?

Your furnace heats for several minutes, then the air turns cold before the house reaches the temperature you've set.

The burners may have shut off early while the blower keeps running. Overheating or a faulty control can cause this.

If the furnace keeps starting over without heating the house, call Blake Brothers for heating repair rather than repeatedly resetting it.

Is It Normal for a Furnace to Blow Cool Air Briefly?

Some furnaces move cooler air through the vents at the beginning or end of a heating cycle.

That should only last a short time. Once the burners are heating, warm air should reach your rooms.

Can a Dirty Filter Cause a Furnace to Blow Cold Air?

Yes. Severe airflow restriction can shut off the heat while the blower continues running.

If replacing the filter doesn't restore heat, the furnace needs professional service.

When Should You Call for Furnace Repair?

Call Blake Brothers when:

• Cold air continues after checking the thermostat and filter.
• Your furnace starts and stops every few minutes.
• The house won't reach the thermostat setting.
• You hear grinding, banging, or scraping.
• The equipment shuts down repeatedly.

If your house uses a heat pump instead of a furnace, ask about heat pump repair. The two systems have different heating parts and repair needs.

When Is a Furnace Problem an Emergency?

If you smell gas or your carbon monoxide alarm sounds, leave the house immediately. Call 911 or your gas utility from outside.

For an electrical burning smell, turn off the furnace if it's safe and leave it off until it's inspected.

Complete heat loss can also become urgent when someone in the house is at risk from falling indoor temperatures.

Should You Repair or Replace the Furnace?

One breakdown doesn't mean you need a new furnace. If the equipment has been dependable and the problem can be repaired, keeping it makes sense.

Repeated breakdowns, major damage, or a furnace that still struggles to heat the house after repairs are reasons to consider furnace replacement.

Furnace Repair in Huntsville & North Alabama

Blake Brothers provides HVAC services throughout Huntsville and North Alabama. Our technicians repair furnaces that won't start, stop heating, or keep shutting down.

Contact Blake Brothers to schedule furnace service.