You are in Georgia. Visit Alabama. Visit Tennessee.

You are in Georgia. Visit Alabama. Visit Tennessee.

You are in Georgia. Visit Alabama. Visit Tennessee.

You are in Tennessee. Visit Georgia. Visit Alabama.

You are in Tennessee. Visit Georgia. Visit Alabama.

You are in Tennessee. Visit Georgia. Visit Alabama.

You are in Alabama. Visit Georgia. Visit Tennessee.

You are in Alabama. Visit Georgia. Visit Tennessee.

You are in Alabama. Visit Georgia. Visit Tennessee.

Furnace Troubleshooting: 4 Quick Fixes Before Calling a Pro

Would you like to spend $100 to be told the obvious? No?

Didn’t think so. But that’s often what happens when Atlanta homeowners call us for a furnace repair.

Often the “problem” is caused by a minor issue that they could have fixed, saving themselves the cost of the service call.

So if your furnace isn’t working as it should, hold off that service call! Try these 4 simple troubleshooting tasks first. Of course, if they don’t fix your problem, call us for help.

  • Check your thermostat for issues
    Furnace not coming on? Check the thermostat first and do these tasks:
    • Make sure the thermostat is set to “heat” and not “cool”
    • Turn the thermostat at least 5 degrees higher than the room temperature
    • Replace the thermostat’s battery
    • Open the thermostat and gently blow out any dust or dirt that has accumulated

Now, if the furnace is blowing cool air sometimes, you want to check the thermostat fan setting to make sure it’s on “auto,” not “on.” The “on” setting will cause the blower to run constantly, even if the furnace is not heating the air.

  • Check the furnace filter
    Is your furnace shutting down randomly? Does it run for a long time and never seem to heat the home? Is the air coming out of your vents weak?

    You may have a dirty furnace filter.

    A dirty furnace filter restricts airflow over the furnace’s heat exchanger, causing several problems:
    • Heat exchanger overheats and shuts down.
    • Soot can build up on the heat exchanger, lowering your furnace’s efficiency.
    • Reduces airflow coming out the vents. So the furnace is running, but you’re never comfortable.

Your owner’s manual should show you where the furnace filter is and how to replace it. Check the filter at least once a month and change it, if needed.

So when is a filter “too dirty” to keep around? Hold the filter up to the light. If you can’t see light coming through it clearly, replace it.

  • Check circuit breakers and shutoff switches
    Does your furnace refuse to turn on no matter what temperature you set it to?

    It may be turned off. A few places to check include:
    • A standard wall switch near the furnace. It should look just like a light switch.
    • The circuit breaker panel. Look for the switch with a furnace label next to it. If the switch is in the middle position, it’s tripped. Turn it to the “off” position and then “on.” If the circuit breaker trips again, you have another issue you need to fix (like replacing the air filter.)
    • The front panel covering the blower. Make sure the panel is shut all the way; there’s a switch under the panel that needs to be depressed for the furnace to work.
  • Open any closed air vents
    Homeowners often close air vents in unused rooms to save money.

    However, closing vents in any rooms actually causes the opposite to happen: it wastes money— and it can cause the furnace to shut down, too!


    Well, your furnace is sized to heat your entire home, unused rooms and all. Closing vents does not decrease the amount of air the blower pushes out. It just increases pressure in the air duct system.

    (Imagine trying to run while breathing with only one nostril. You’re still trying to move the same amount of air, but now there’s way more pressure traveling through that one nostril.)

    This extra pressure in the duct system causes several issues you may be having:
    • Less comfortMost homes have air duct leaks, allowing your conditioned air to escape. Extra air pressure in the ducts pushes more air out through the leaks—or even worse—creates more air leaks. That means there’s less air getting to certain parts of your home.
    • Furnace keeps shutting down— The extra pressure causes the blower to work at a lower speed. This decreases air over the heat exchanger, causing it to overheat and shut down. It’s just like having a dirty air filter.

Still need help?

If these 4 tasks didn’t solve your furnace problem, and you live in the Atlanta area, call Coolray for help. Scheduling online saves you 10% on repairs.

Coolray is your Atlanta-area home comfort expert with specialists in heating, air conditioning, air quality and plumbing. Have more questions? We’d be happy to help – just contact us online.

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