Why is My Furnace Blowing Cold Air?

Cold air blowing from the air vents is one of the most common furnace problems Utah homeowners experience. Discover the possible reasons why your heater is blowing cold air and some troubleshooting tips to help you heat things up again.

Cold Air in the Ducts

When the furnace comes on for the first time in a while, it has to push out all the cold air sitting in the ducts before it can feel warm. This is similar to waiting for the water to heat up at the tap. Before you start troubleshooting, give it a few minutes and see if the air heats up on its own.

Wrong Thermostat Settings

If someone has messed with the thermostat, the furnace might now be blowing cold air instead of hot. First, make sure it’s set to heating mode. Then, check whether the fan is “on.” This means the blower will run even when the burner isn’t lit, circulating room-temperature air around your home. Change the fan setting to “auto” if you prefer to only have the fan and furnace run at the same time.

No Pilot Light or Faulty Electronic Ignition

You could have a furnace blowing cold air because of an ignition problem. Older gas furnaces ignite the burner with a constantly burning pilot light. If it goes out, you must relight it. Newer gas and electric furnaces use more energy-efficient electronic ignition. If your igniter is faulty, you may need to have an HVAC technician replace it to get your furnace working again.

Leaky or Uninsulated Ductwork

The cold air coming from your air registers may not be related to the furnace. Instead, the ductwork could be to blame. Air leaks are a common issue, allowing cold air from unconditioned spaces to flow into your home. Lack of ductwork insulation is also problematic. If the air feels coldest in the most far-flung rooms of your home, uninsulated air ducts are a likely culprit.

Blocked Fuel Supply

A bad natural gas valve or empty onsite propane or oil tank could cause your furnace to blow cold air. Check your fuel supply and refill it, if necessary, to keep your home warm.

Bad Thermostat or Circuit Control Board

When the heating cycle turns on, the thermostat sends a message to the circuit control board inside the furnace. If either device is faulty, the blower may turn on, but not the furnace. As a result, the heater blows cold air. Seek help from an HVAC technician to fix this problem.

Once you have exhausted all your troubleshooting options, it’s time to seek advice from a certified HVAC technician. Parley’s PPM Plumbing, Heating & Cooling has you covered. Our team draws from over 40 years of experience repairing furnace problems of all kinds. Call us today at 801-877-2184 if you live in Utah County, or reach out to us at 801-877-2536 if you’re a Salt Lake County resident. You can also contact us online for more tips or request an appointment.