furnace repair

What to do When Your Furnace Will Not Turn On

It might feel scary 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 many of these fixes are fast and inexpensive (or even free).

This checklist 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 Grove City, Air Quality Solutions can lend a hand.

We service 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 usually caused by forgotten routine maintenance. These evaluations often reveal a high-cost problem before it gets worse—and causes your HVAC system to fail.

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

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

Steps for Troubleshooting Your Furnace

Inspect Your Thermostat

Start by looking at your thermostat. Is it telling your furnace to switch on?

If you have a digital thermostat:

  • Replace the batteries if the screen is off. 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.”
  • Find out if the program is showing the current day and time and is set to “run.” If you can’t override the program, fix the temperature by pushing the up/down arrows and press the “hold” button. This will force the furnace to turn on if thermostat programming is causing an issue.
  • Set the temperature to 5 degrees warmer than the room’s temperature.
Digital Thermostat

Your furnace should start within a few minutes. If it doesn’t, make sure it has power by moving the fan switch from “auto” to “on.” If the fan doesn’t start right away, your furnace may not have access to power.

If you’re connected to a Wi-Fi thermostat—like one made by Nest, Ecobee, Lux, Honeywell or Bosch—turn to the manufacturer’s website for advice. If you can’t get your smart thermostat to work, call us at 614-871-4144 for help.

Smart Thermostat

Check Breakers and Switches

After that, you will need 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 handling the panel or breakers.
  • Locate the breaker labeled “furnace” or “heat” and make sure that it’s switched in the “on” position. If the breaker has tripped, it will be in the midpoint or “off” position.
  • With one hand, firmly push 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 Quality Solutions at 614-871-4144 right away.

Your furnace has at least one wall switch located on or near it—no matter how old it is or who made 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 to find your furnace? Look in your basement, garage or utility closet. It could also be in a crawl space or attic.)

Replace Your Air Filter

Dirty, clogged air filters often create issues that are easily avoidable.

  • Your furnace can overheat and turn off 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 extra dirty filter can cue 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 location depends upon what model of furnace you have.

Replace furnace filter

When switching out your filter:

  • Shut off your furnace completely.
  • Grab the filter, hold it up to the light and look through it. Replace it 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 easier in the future, use a permanent marker on your furnace housing or ductwork to indicate the airflow direction and filter size.

We recommend replacing flat filters each month. Pleated filters usually last about three months. You can also get a washable filter that will last about 10 years.

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

Look at Your Condensate Pan

Condensate pans, or drain pans, hold water your furnace takes 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: Make sure that it’s open. 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: Take a look at the float switch. If the switch is “up” and there’s fluid in the pan, call us at 614-871-4144. You will likely need an updated pump.

Check Inside Your Furnace

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

Call us at 614-871-4144 if you see anything other than a steady, colored light or blinking green light. Your furnace is probably giving an error code that demands professional service.

Clean Your Flame Sensor

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

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

Want to try 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 as well if your gas valve is not electric.
  • Open your furnace’s front panel and trace 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 switched out for a new one. Or something else could be wrong. Call us at 614-871-4144 for assistance if this happens.

Relight the Pilot Light

If your furnace is an older style, its pilot light could be extinguished. Relight it following the instructions on the label. You can read 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.
  • Release the “reset” button once the pilot light is lit.

Reach out to us at 614-871-4144 if you’ve followed the steps 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 start?

Call us today at 614-871-4144 or use our online scheduler. We’ll come out to your home and find out what’s wrong.

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