furnace repair

What to do When Your Furnace Will Not Turn On

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

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

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

When you require a pro in East Bernard, E.B. Air, LLC can lend a hand.

We service most makes and models of furnaces. If you need an updated heating system, we also offer furnace replacement and furnace installation.

Furnace breakdowns are generally caused by a lack of routine maintenance. These evaluations often reveal an expensive problem before it begins—and causes your HVAC system to fail.

During this service, our NATE-certified professionals will carefully 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 costs.

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

Steps for Troubleshooting Your Furnace

Take a Look at Your Thermostat

Start by examining your thermostat. Is it telling your furnace to turn on?

If you have a digital thermostat:

  • Switch out the batteries if the screen is off. If the digital screen is scrambled, you may need to replace your thermostat.
  • Check that that the switch is set to “heat” instead of “off” or “cool.”
  • Look to see if the program is presenting the current day and time and is set to “run.” If you can’t override the program, fix the temperature by using the up/down arrows and press the “hold” button. This will compel the furnace to turn 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 shortly. If it doesn’t, make sure it has power by pushing the fan switch from “auto” to “on.” If the fan doesn’t start 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 help. If you can’t get your smart thermostat to work, call us at 979-335-4262 for assistance.

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 touching the panel or breakers.
  • Locate 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 midpoint or “off” position.
  • With one hand, firmly move the breaker to the “on” position. If the breaker trips and pops back to “off” after you do this, leave it alone. Contact a technician from E.B. Air, LLC at 979-335-4262 as soon as possible.

Your furnace has at least one wall switch situated 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 get working if the switch was off. (Not sure where your furnace is located? Look in your basement, garage or utility closet. It could also be placed in a crawl space or attic.)

Replace Your Air Filter

Dirty, closed off air filters often cause issues that are easily avoidable.

  • Your furnace can overheat and stop working too soon, due to dust in the filter restricting airflow.
  • Your energy bills could increase, because your furnace is working 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 prompt the breaker to trip.

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

Replace furnace filter

When replacing your filter:

  • Turn 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.
  • Put in the new filter with the arrow pointing toward the furnace to avoid damage.

To make the process less difficult for yourself, use a permanent marker on your furnace housing or ductwork to indicate the airflow direction and filter size.

We recommend replacing flat filters monthly. Pleated filters typically 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 switch out your filter more often.

Check Out Your Condensate Pan

Condensate pans, or drain pans, hold water your furnace removes 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 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 979-335-4262. You will probably 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 type, this light could be placed on the outside of your furnace.

Contact us at 979-335-4262 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 trying to start but shutting down without blowing heat? A filthy flame sensor could be at fault. When this takes place, 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 comfortable opening up your furnace. We can also do it for you.

Ready to take on 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.
  • Take off your furnace’s front panel and follow 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.
  • Put back 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 regularly. If it doesn’t turn on, the sensor might need to be replaced. Or something else could be the problem. Call us at 979-335-4262 for assistance if this happens.

Relight the Pilot Light

If your furnace is an older style, its pilot light could be blown out. Relight it following the instructions on the label. You can locate 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 move the flame of a long lighter to the pilot light opening.
  • Let go of the “reset” button once the pilot light is lit.

Call us at 979-335-4262 if you’ve followed the guide twice and the pilot won’t light or stay lit.

Check Your Fuel Source

Are other gas appliances functioning? 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 979-335-4262 or use our online scheduler. We’ll come out to your home and figure out what’s wrong.

*Required fields