Troubleshooting a Furnace Fan That Blows Cold Air

If your furnace fan intermittently blows cold air or stops blowing warm air all at once, check a few things before calling a professional. Local residential furnace installation expert Sierra Air shares some troubleshooting steps that you should do in this case.

Check the Duct System

While the furnace is running, check the ductwork for possible areas where heat loss may occur. Look out for long uninsulated runs, missing or damaged insulation, and possible air leaks at the return vents. If you find any of these issues, have them addressed. Having a functional furnace won’t matter if it will keep losing heat along the way.

Check the Air Filter and Registers

Next, check the air filters. Clogged filters can reduce the amount of air that passes through your heating system. Clean or replace them if disposable. Check the vents and registers, and make sure they’re not obstructed by furniture and other equipment. Test the furnace again, and see if this makes an improvement.

Check If Air Conditioner Is Turned On

This may sound ridiculous, but it nevertheless is a common mistake, especially for homes with completely independent heating and cooling systems. Take a moment to check if the air conditioner is accidentally turned on, and check the thermostat to see if it was accidentally set to cooling. If it’s the latter, consider investing in smart thermostats, which are common in modern furnace installations. These electronic thermostats “learn” your usage habits and ensure that your HVAC settings are set to the correct season.

Check the Fan Limit Switch

If none of these solutions work, inspect your furnace, and look for the fan limit switch. Try turning the upper limit to a few degrees higher, and check if the dial moves. Wait a few minutes, and then check if the fans are blowing hot air. If so, put the limit switch to where it was, and check again. If the hot air stops again, the fan limit switch may faulty and will have to be replaced.

Easy HVAC Troubleshooting With Sierra Air

For furnace repairs and your other HVAC needs, call Sierra Air today at (775) 800-5500. You can also fill out our contact form to schedule an appointment.