Troubleshooting 101: Why is My Furnace Blowing Cold Air?

A working furnace is an important part of a healthy and comfortable home. When your heating system breaks down and starts blowing cold air, it can be difficult to know exactly what’s wrong.

Your furnace may be blowing cold air for a number of reasons. The air filter may be dirty and blocking airflow, you may have a faulty electrical component, or you may have a more serious issue like a leak or clogged condensate line.

Read this troubleshooting guide to narrow down what’s causing your furnace problems.

Common Causes of Furnaces Blowing Cold Air

Maybe your furnace intermittently blows cold air and hot air. Or, your furnace may not give off any heat. In certain situations, your furnace may not turn on at all. Here are a few possible reasons your furnace is acting up:

• Incorrect thermostat setting
• Faulty thermostat
• Overheated system
• Extinguished pilot light
• Dirty air filter
• Dirty furnace burners
• Worn flame sensor

Furnaces are complex heating components, but you don’t have to be an HVAC technician to troubleshoot your system. Follow the steps below to determine what’s causing your heating issues.

Furnace Troubleshooting Guide

1. Check the thermostat fan settings: Make sure that the thermostat fan dial is turned to AUTO, not ON. This will ensure the heater only runs when the furnace has had a chance to heat the air.
2. Check the air filter: The air filter is one of the most commonly overlooked parts of the furnace. A dirty filter can cause the heat exchanger to overheat, which in turn causes the burners to switch off, leaving you without heat. Once you replace the dirty filter, call an HVAC technician to help you reset your system.
3. Check the control panel: Sometimes a faulty electronic component in the control panel can affect your heating system. Try powering your furnace off, waiting a few minutes, then turning it back on again.
4. Check the pilot light: If you have a gas furnace that’s blowing cold air, the pilot light may be to blame. When it goes out, your furnace stops being able to output heat as it should. If your pilot light is extinguished, carefully follow your furnace’s instructions for relighting. If it won’t stay lit, call a professional furnace technician for assistance.
5. Check the ducts for leaks: A leak in your air ducts can cause valuable heated air to escape your home. This means that the air coming out of your vents will not feel as warm as usual.
6. Check for standing water: Some types of furnaces produce condensation, which drains out through a condensate line. If there’s something blocking the flow of water, such as a clog or leak, you may see standing water around the bottom of your furnace. This water will likely trigger the power switch to prevent further damage. Call a technician before attempting to reset your furnace.

Expert Furnace Repair in Portland, OR

If your furnace is acting up, turn to the heating experts at Roth Home. We’re the most trusted HVAC company in Portland, Salem, and the surrounding communities, and we’re here to keep you comfortable.

Our technicians are committed to providing excellent furnace repair, no matter what the problem may be.

Give us a call at 503-266-1249 to schedule an appointment.