Why is My Furnace Blowing Cold Air?

Common Answers for Coachella Valley Area Homeowners

Imagine this: You’re relaxing on the living room couch and it begins to get a bit too cold in your house. You are relieved to hear the sound of your furnace kicking on, and you feel a light breeze coming from your air registers. After a minute or two passes by, you begin realize a big problem: the air coming from your furnace is cold! Today we’re going to talk about why your furnace would start blowing cold air and what you can do to take care of the problem!

Why is my furnace blowing cold air? Answers with easy fixes

Although it’s definitely concerning when your furnace is blowing cold air, there are a few explanations that can be taken care of quickly and easily on your own. These include:

• It’s the beginning of a heating cycle. When you turn on the shower, you don’t expect hot water to instantly come out of your taps. The same is true for your ductwork. When your furnace is idle, the air in your ducts cools down. When a heating cycle begins again, that cool air will be the first thing that’s pushed out of your registers. This cool air should be quickly replaced by warm air, so wait a minute to ensure that your furnace is indeed working.
• Your fan is set to “on” instead of “auto.” Your thermostat has a switch for your fan that can be set to “on” or “auto.” If this switch is set to “on,” your fan will be blowing constantly, even if your furnace is not in a heating cycle. This will cause cool air to come out of your registers. You can fix this problem by simply changing the setting to “auto.”
• Your pilot light went out. If you have an older furnace with a pilot light, the light might go out during a heating cycle. When this happens, the thermocouple will shut off the gas supply to your burners and your furnace’s fan might continue to run without a heat supply. You can fix this by relighting your pilot light. If your pilot light continues to blow out, contact Hydes.

Why is my furnace blowing cold air? Answers that will require a professional

There are also some more advanced issues that can develop with your furnace that cause it to blow cold air. These issues will need to be addressed by a professional heating contractor like Hydes:

• Dirty flame sensor. Your furnace has a sensor that detects whether or not the burners are lit. If that sensor does not detect a flame, it will shut off the gas supply to your furnace. Flame sensors can get dirty over time, especially if you have a dirty air filter or you skip your annual tune-ups. A dirty flame sensor might tell your burners to shut off even if the burners are working just fine, which will cause your furnace to blow unheated air.
• Malfunctioning limit switch. Another device that can malfunction and cause your furnace to blow cold air is the limit switch. The limit switch tells your furnace’s fan when to turn on and off. If this switch is not working properly, your fan might turn on too early in a heating cycle or keep running after a heating cycle has ended, both of which will cause your furnace to blow cold air.

If you have any questions about why your furnace is blowing cold air, or if you’d like a heating system serviced or installed in your home, contact Hydes, your Coachella Valley furnace installation and repair contractor.