Diagnosis
When your furnace blows cold air instead of warm, it usually means something is preventing it from igniting its main heating components. This could be a pilot light that has gone out, a dirty flame sensor that can't confirm a flame, or even a simple thermostat setting that needs adjustment. These safety features prevent the furnace from running when it can't detect a flame, leaving your home without heat, which can be quite uncomfortable and even risky in chilly weather.
Tools Needed
- Screwdriver set
- Vacuum cleaner with hose attachment
- Clean cloths
- Furnace filter
- Work gloves
Warnings
- Always turn off the power to the furnace at the breaker box before opening any panels or working on internal components.
- Be cautious of sharp metal edges inside the furnace. Wear work gloves to protect your hands.
- If you smell gas, turn off the furnace immediately, leave the area, and call your gas company or 911.
Step-by-Step Instructions
- First, check your thermostat. Ensure it's set to 'Heat' and that the desired temperature is above the current room temperature.
- Next, locate your home's breaker box and turn off the power to the furnace.
- Find the furnace filter. If it appears clogged or dirty, replace it with a new one.
- Locate the access panel on your furnace, typically found on the lower or side section. You'll likely need a screwdriver to remove it.
- Look for the pilot light assembly. If the pilot light is out, consult your furnace's manual for specific instructions on how to relight it. This usually involves holding a button while igniting.
- If the pilot light stays lit, but your furnace continues to blow cold air, find the flame sensor. It's a metal rod usually positioned near the burners.
- Carefully remove the flame sensor, likely with a screwdriver. Gently clean it using a soft cloth or very fine-grit sandpaper.
- Reinstall the cleaned flame sensor and reattach the furnace's access panel.
- Go back to your breaker box and restore power to the furnace.
- Finally, set your thermostat to call for heat. Your furnace should now ignite and begin blowing warm air.
Troubleshooting
- If the furnace still blows cold air after cleaning the flame sensor, check if the ignitor is glowing. If not, the ignitor may need replacement.
- Listen for clicking sounds that might indicate the gas valve is trying to open. If you hear clicking but no ignition, the gas valve might be faulty.
- Ensure the furnace's condensate drain line isn't clogged, as some safety systems will shut down the furnace if this occurs.
Alternative Method
If your furnace has an electronic ignition (no pilot light), the issue might be with the ignitor itself. You can try cleaning the ignitor, or if that doesn't work, it may need to be replaced by a professional.
Preventive Tips
- Replace your furnace filter regularly, typically every 1-3 months, depending on the filter type and your home environment.
- Schedule annual professional maintenance for your furnace to ensure all components are clean and functioning correctly.
- Keep the area around your furnace clear of clutter to ensure proper airflow and easy access for maintenance.
Brief Summary
This guide provides a step-by-step process for addressing a furnace that is blowing cold air. It covers essential checks like the pilot light, flame sensor, and thermostat settings, offering clear instructions for homeowners to restore warmth to their homes.
Content Details
Keywords: furnace, cold air, heating, pilot light, thermostat, repair, troubleshooting
Meta Description: Furnace blowing cold air? Follow our easy-to-understand guide to diagnose and fix the problem, covering thermostat settings, pilot lights, and flame sensors.