furnace repair

What to do When Your Furnace Wont Turn On

It might seem stressful to troubleshoot your furnace when your heat won’t work. But it doesn’t have to be that way.

You may be able to skip a furnace repair call with our DIY troubleshooting guide. You don’t need any industry skills. And the majority of these fixes are brief and low-cost (or even free).

This guide will walk you through how to fix your furnace when it won’t switch on, won’t stay on or won’t light.

When you require a pro in Middle Georgia, Air Concepts of Middle Georgia can lend a hand.

We repair and maintain most makes and models of furnaces. If you need a more modern heating system, we also offer furnace replacement and furnace installation.

Furnace breakdowns are often caused by a lack of routine maintenance. These checkups often reveal an expensive problem before it gets worse—and causes your HVAC system to stop working.

During our visit, our NATE-certified professionals will thoroughly inspect your furnace, make sure it’s working properly and lubricate moving parts. A well-managed furnace often lasts longer and operates more efficiently, saving you more on your heating charges.

Ready to tackle troubleshooting your furnace? Follow our step-by-step guide below.

Steps for Troubleshooting Your Furnace

Inspect Your Thermostat

Start by checking your thermostat. Is it telling your furnace to start?

If you have a digital thermostat:

  • Change the batteries if the screen is unresponsive. If the digital screen is scrambled, you may need a different thermostat.
  • See if that the switch is set to “heat” instead of “off” or “cool.”
  • Make sure the program is showing the correct day and time and is set to “run.” If you can’t change the program, fix the temperature by using the up/down arrows and press the “hold” button. This will require the furnace to switch on if thermostat programming is causing a problem.
  • Set the temperature to 5 degrees warmer than the room’s temperature.
Digital Thermostat

Your furnace should turn on fairly quickly. If it doesn’t, make sure it has power by sliding the fan switch from “auto” to “on.” If the fan doesn’t run right away, your furnace may not be connected to power.

If you’re connected to a Wi-Fi thermostat—like one made by Nest, Ecobee, Lux, Honeywell or Bosch—check the manufacturer’s website for advice. If you can’t get your smart thermostat to turn on, call us at 478-200-5689 for help.

Smart Thermostat

Check Breakers and Switches

If you’ve already checked your thermostat, you will want to make sure your breakers and furnace switch are on.

  • Go to your house’s main electrical panel. It’s the gray metal box on the wall in your basement, garage or closet.
  • Dry off your hands and feet before working with the panel or breakers.
  • Pinpoint the breaker labeled “furnace” or “heat” and confirm that it’s switched in the “on” position. If the breaker has tripped, it will be in the center or “off” position.
  • With one hand, firmly shift the breaker to the “on” position. If the breaker trips and pops back to “off” after you do this, leave it alone. Contact an expert from Air Concepts of Middle Georgia at 478-200-5689 right away.

Your furnace has at least one wall switch placed on or near it—no matter when it was made or who manufactured it.

  • This switch should be flipped up in the “on” position. It can take your furnace up to five minutes to start if the switch was off. (Not sure where your furnace is? Look in your basement, garage or utility closet. It could also be located in a crawl space or attic.)

Replace Your Air Filter

Dirty, blocked air filters often cause complications that are easily avoidable.

  • Your furnace can overheat and stop working too soon, due to dust in the filter hampering airflow.
  • Your energy bills could get more expensive, because your furnace is turning on more often.
  • Your furnace may fail permantly faster, because it has to work harder.
  • Your furnace could lose power, because an excessively dirty filter can prompt the breaker to trip.

You can find your air filter inside your furnace’s blower component, attached filter case or wall-mounted return air grille. Its placement depends upon what type of furnace you have.

Replace furnace filter

When replacing your filter:

  • Turn off your furnace completely.
  • Pick up the filter, hold it up to the light and look through it. Get a new filter if you can’t see light through it.
  • Replace the new filter with the arrow pointing toward the furnace to avoid damaging your system.

To make the process simpler in the future, use a permanent marker on your furnace housing or ductwork to indicate the airflow direction and filter size.

We advise replacing flat filters monthly. Pleated filters usually last about three months. You can also get a washable filter that will work for about 10 years.

If you have children or pets, you may need to switch out your filter more frequently.

Inspect Your Condensate Pan

Condensate pans, or drain pans, capture water your furnace pulls from the air.

Follow these steps if your furnace is dripping water or there’s standing water in the pan.

  • If your pan has a PVC pipe/drain: Check that it’s clear. If it’s not, you can use a special pan-cleaning tablet from a home improvement or hardware store.
  • If your pan has a pump: Check out the float switch. If the switch is “up” and there’s water in the pan, call us at 478-200-5689. You will most likely need an updated pump.

Check Inside Your Furnace

You can check the quality of your furnace’s blower motor by checking inside the plastic window. Depending on the kind, this light could be placed on the outside of your furnace.

Call us at 478-200-5689 if you see anything other than a stable, colored light or blinking green light. Your furnace is likely giving an error code that needs professional help.

Clean Your Flame Sensor

Is your furnace making an effort to start but turning off without blowing heat? A dirty flame sensor could be at fault. When this happens, your furnace will try to turn on three times. Then, a safety feature will shut it down for about an hour.

You can clean the flame sensor yourself if you feel comfortable opening up your furnace. We can also do it for you.

Want to tackle cleaning the sensor yourself? You’ll need the following:

  • A 1/4” hex screwdriver or wrench
  • Piece of light-grit sandpaper, steel wool or emery cloth
  • A dry, clean paper towel

Next:

  • Use your furnace’s wall switch or breaker to shut off the power. Shut off the gas also if your gas valve is not electric.
  • Open your furnace’s front panel and track the wire to the flame sensor, which looks like a thin, bent rod.
  • Unscrew the rod and use your sandpaper, steel wool or emery cloth to gently clean the metal rod.
  • Use a paper towel to wipe off the rod.
  • Remount the sensor.
  • Put your furnace’s doors back on.
  • Turn the furnace’s power back on. Your furnace may run through a series of checks before it starts normally. If it doesn’t start, the sensor might need to be replaced. Or something else could be the problem. Call us at 478-200-5689 for assistance if this happens.

Relight the Pilot Light

If your furnace is an older design, its pilot light could be extinguished. Relight it following the instructions on the label. You can find the label on your furnace’s doors.

Or you can follow these steps:

  • Locate the switch on the bottom of your furnace labeled “pilot,” “on” and “off.”
  • Rotate the switch to the “off” position.
  • Wait at least five minutes. This avoids the possibility of starting a fire.
  • Turn the knob to “pilot.”
  • Hold down the “reset” button as you deliver the flame of a long lighter to the pilot light opening.
  • Stop holding the “reset” button once the pilot light is lit.

Contact us at 478-200-5689 if you’ve followed the instructions twice and the pilot won’t light or stay lit.

Check Your Fuel Source

Are other gas appliances working? If they’re not, your natural gas service could be off. Or you could be out of propane.

We Can Diagnose Furnace Problems

Made it through our troubleshooting guide but your furnace still won’t work?

Call us today at 478-200-5689 or use our online scheduler. We’ll come out to your home and identify what’s wrong.

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