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

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

When you need a pro in Odessa, Redhawk Heating & Air Conditioning can be there.

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 often caused by forgotten routine maintenance. These evaluations often reveal a costly problem before it starts—and causes your HVAC system to fail.

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

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

Steps for Troubleshooting Your Furnace

Check Your Thermostat

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

If you have a digital thermostat:

  • Switch out the batteries if the screen is unresponsive. If the digital screen is scrambled, you may need to replace your thermostat.
  • Confirm that the switch is set to “heat” instead of “off” or “cool.”
  • Find out if the program is displaying the right day and time and is set to “run.” If you can’t alter the program, change the temperature by pushing the up/down arrows and press the “hold” button. This will force the furnace to start if thermostat programming is causing complications.
  • Set the thermostat to 5 degrees warmer than the room’s temperature.
Digital Thermostat

Your furnace should kick on within a few minutes. If it doesn’t, see if it has power by sliding the fan switch from “auto” to “on.” If the fan doesn’t work instantly, your furnace may not be connected to power.

If you’re utilizing 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 432-237-0168 for support.

Smart Thermostat

Check Breakers and Switches

If you’ve already checked your thermostat, 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 working with the panel or breakers.
  • Find 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 move the breaker to the “on” position. If the breaker trips and goes back to “off” after you do this, leave it alone. Contact a technician from Redhawk Heating & Air Conditioning at 432-237-0168 immediately.

Your furnace has at least one wall switch situated on or near it—no matter its age or brand.

  • 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 cause issues 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 increase, because your furnace is working more often.
  • Your furnace may have a shorter life span, because it has to work harder.
  • Your furnace could lose power, because an extra dirty filter can cue 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 placement depends upon what type of furnace you have.

Replace furnace filter

When replacing your filter:

  • Shut down your furnace completely.
  • Pull out 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.
  • Install the new filter with the arrow pointing toward the furnace to avoid damaging your system.

To make the process easier next time, 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 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 change your filter on a more regular basis.

Look at Your Condensate Pan

Condensate pans, or drain pans, catch 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: 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: Find the float switch. If the switch is “up” and there’s fluid in the pan, call us at 432-237-0168. You will likely need an updated pump.

Peek Inside Your Furnace

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

Call us at 432-237-0168 if you see anything other than a solid, 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 making an effort to start but turning off without blowing heat? A dirty flame sensor could be at fault. When this occurs, your furnace will try to switch 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.

Ready 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 turn off the power. Shut off the gas as well if your gas valve is not electric.
  • Remove 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.
  • Replace 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 switched out for a new one. Or something else could be the issue. Call us at 432-237-0168 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 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.
  • Move the knob to “pilot.”
  • Hold down the “reset” button as you bring the flame of a long lighter to the pilot light opening.
  • Stop holding the “reset” button once the pilot light is lit.

Call us at 432-237-0168 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 432-237-0168 or use our online scheduler. We’ll come out to your home and identify what’s wrong.

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