Furnace Repair: What To Do if Your Furnace is Giving You No Error Code

Do you ever feel like your furnace is playing tricks on you? At times, it’s a little shy about letting you know when there’s an issue. It might give subtle warning signs, like the temperature in your home climbing up quickly. Then again, it may simply stop working without any prior notice or visible sign of trouble. In the case of a silent or uncooperative furnace, not getting an error code from its diagnostic check isn’t necessarily good news. If your gas furnace won’t light but isn’t giving you an error code during its self-check ritual, that generally means something is wrong with the furnace control board. If your electric furnace won’t start and isn’t giving you any error messages, it could be a sign that there is some kind of mechanical failure preventing it from operating as expected.

Check the obvious.

You might have a loose wire that is preventing your furnace from getting the power it needs to operate (again if it’s electric). Or, perhaps a critter has made its way into your ductwork and is chewing on a wire. A clogged filter can also cause your furnace to shut down. You can also use a thermostat to manually shut off your furnace if it’s not working. To do so, simply turn the thermostat down to 80 degrees. This will shut off your furnace.

Confirm your furnace isn’t giving you an error code.

If you do have a gas furnace, you may not see an error code on the display, but you should see the word “clearing” at some point in the self-diagnostic cycle. If you have an electric furnace and the diagnostic light is not on, or flashing, you may need to turn your furnace off and on again, which may clear any error codes. If your furnace continues to not indicate an error, it’s time to call a pro.

Your next step: Call a pro.

If your furnace is not giving you an error code and there is no clear indication of what’s wrong with it, it’s time to call a pro. Your furnace repair technician will be able to give you an idea of the nature of the problem and what might be required to fix it.

A bad controller means you replace the entire furnace.

If your furnace is not giving you an error code but the controller is fried, you’ll likely need a new furnace—not just a new controller. This could be a sign that the furnace is on its last leg and due for replacement anyway.

Mechanical failure means it’s time for a new furnace.

If you’re getting no error code from your furnace but it just isn’t starting up, the motor may be faulty. If this is the case, you’ll likely need to replace the furnace, since repairing it is unlikely to be cost-effective. When your furnace isn’t giving you an error code, it’s worth taking a moment to consider what might be going wrong. If you can narrow down the cause of the problem and/or rule out some of the more obvious issues, you’ll have a better sense of what you’re up against. At the same time, some issues can be difficult to diagnose. In these cases, it’s best to call a pro.