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Your Go-To Furnace Troubleshooting Checklist

Does it seem like your furnace has the uncanny ability to stop working at the worst times? Fortunately for our customers, many of the furnace calls we get can be solved in a matter of minutes—sometimes over the phone! For this reason, we wanted to put together some simple steps that our customers can follow to help get their heaters up and running again when there are no major mechanical issues involved.

Having trouble with your furnace? Use this troubleshooting checklist to solve basic furnace problems in a pinch.

1. First, check your thermostat.

Your thermostat is the “command center” for your heating system. If it’s not working, neither with your furnace.

  • Is the display blank? Replace the batteries. Also, make sure that the circuit breaker associated with the thermostat hasn’t been tripped. If it has, flip the switch back into the “on” position.
  • Is the display on but not responding or acting strangely? Again, this could be a battery issue, so try replacing the batteries. If you own a Wi-Fi thermostat, make sure the device is connected to your home’s Wi-Fi network AND that it has received all the latest updates from the manufacturer. Updates can help “debug” issues that have been brought to the manufacturer’s attention.
  • If you can’t get your thermostat to respond no matter what, it may have a defect or faulty wiring. At this point, you will need a technician’s help.

If your thermostat is responding, look at the settings.

  • Is the AC on or the heater? We know this question seems very basic, but trust us: we’ve seen everything.
  • Is the thermostat set to “auto?” If your thermostat is on “auto,” then the furnace should kick on once your home’s temperature falls below your desired temperature on the thermostat. This is typically a good setting for most people.
  • Is the thermostat set to “on?” If your thermostat displays “on,” then this means that the heating system’s fan is on. This means that your system’s fan will blow air continuously throughout your home even when the heater isn’t heating the air. After a while, the air can start to feel colder and colder, which can make it appear as though your furnace is broken, when, in fact, the heat isn’t actually on.

2. Make sure your furnace is receiving power.

If your furnace is still having trouble after you’ve checked the thermostat, it might not be getting electricity. Even if you have a gas- or oil-burning furnace, your heating system’s blower requires electricity to pull in cold air and blow out warm air. Your furnace may also have an ignition system that needs electricity to work.

Check your home’s circuit breaker panel for any tripped breakers. The breaker for your furnace may be labeled something like “furnace,” “heater,” or “FAU” for “forced air unit.” Flip the switch back into the on position and try starting up your furnace again.

3. Try opening and closing the furnace door.

If you’ve followed the steps above and your furnace still won’t turn on, the unit’s door might be the issue. Go to your furnace and try to locate the metal door of the unit itself. Pull it open and then close it again firmly until it fits snugly in place with a snap or a click. In some furnaces, this is a safety mechanism that “tells” the furnace that it’s safe to operate.

While you’re there…

4. Turn on your furnace’s power switch if it’s off.

While checking your furnace’s door, go ahead and check the power switch as well. It will look kind of like a light switch, and it should be located right next to the unit or on the unit. If the switch is off, then that is probably the issue. Turn it on.

While you’re there…

5. Ensure that your furnace is receiving gas. (Gas Furnaces Only)

If the power switch was on, the gas supply might be the issue. There should be a gas line (pipe) leading up to your furnace. On this pipe, there will be a valve with a small lever.

If the lever is in line with the pipe, then the valve is open and allowing gas to pass through. If the lever is forming a cross with the pipe, then the valve is closed and blocking gas. Turn the lever until it’s in line with the pipe so that your furnace can receive gas and try to run your furnace again.

6. Change the air filter.

If your furnace runs briefly before shutting down, your air filter is probably the issue. These are the two most likely problems:

  • The air filter has gotten too dirty and is blocking airflow into your system. Replace the filter with a clean one.
  • Your air filter’s efficiency is too high for your system. The high efficiency allows it to trap tiny particles, but it’s not allowing enough airflow into your system. Try using an air filter with a lower efficiency (MERV) rating.

Still Need Help?

Contact Premier Indoor Comfort Systems, LLC today at (770) 268-2422 for reliable heating repairs throughout Georgia!