furnace repair

What to do When Your Furnace Will Not Turn On

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

You might be able to bypass 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 affordable (or even free).

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

When you have to have a pro in Belton, Bell Air Conditioning Inc. can be there.

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 neglected routine maintenance. These checkups often highlight a high-cost 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 working 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 tackle troubleshooting your furnace? Follow our step-by-step guide below.

Steps for Troubleshooting Your Furnace

Take a Look at Your Thermostat

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

If you have a digital thermostat:

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

Your furnace should kick on fairly quickly. If it doesn’t, double check that it has power by pushing the fan switch from “auto” to “on.” If the fan doesn’t run immediately, 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 work, call us at 254-307-9572 for support.

Smart Thermostat

Check Breakers and Switches

Next, you will want to make sure your breakers and furnace switch are on.

  • Find 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.
  • Find 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 Bell Air Conditioning Inc. at 254-307-9572 immediately.

Your furnace has at least one wall switch placed 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 kick on 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 problems that are easily avoidable.

  • Your furnace can overheat and shut down too soon, due to dust in the filter restricting airflow.
  • Your energy bills could get more expensive, because your furnace is working more often.
  • Your furnace may not last as long, 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 model of furnace you have.

Replace furnace filter

When switching out your filter:

  • Shut down your furnace completely.
  • Pick up the filter, hold it up to the light and look through it. Place a new filter in your system if you can’t see light through it.
  • Replace the new filter with the arrow pointing toward the furnace to avoid hurting your machine.

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

We suggest replacing flat filters once a month. Pleated filters generally 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 replace your filter on a more regular basis.

Check Out Your Condensate Pan

Condensate pans, or drain pans, catch water your furnace removes from the air.

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

  • If your pan has a PVC pipe/drain: Be 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 liquid in the pan, call us at 254-307-9572. You will probably need a new pump.

Peek Inside Your Furnace

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

Contact us at 254-307-9572 if you see anything other than a stable, colored light or blinking green light. Your furnace is probably giving an error code that needs professional service.

Clean Your Flame Sensor

Is your furnace attempting to start but shutting down without generating heat? A filthy flame sensor could be be the reason. When this takes place, 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 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 turn off the power. Shut off the gas as well if your gas valve is not electric.
  • Remove 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.
  • 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 as usual. If it doesn’t kick on, the sensor might need to be replaced. Or something else could be the problem. Call us at 254-307-9572 for help if this happens.

Relight the Pilot Light

If your furnace is an older model, its pilot light could be 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 bring the flame of a long lighter to the pilot light opening.
  • Release the “reset” button once the pilot light is lit.

Contact us at 254-307-9572 if you’ve followed the guide twice and the pilot won’t light or stay lit.

Check Your Fuel Source

Are other gas appliances operating? 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 turn on?

Call us today at 254-307-9572 or use our online scheduler. We’ll come out to your home and find out what’s wrong.

*Required fields