furnace repair

St. Louis is Getting Cold, but My Furnace Wont Turn On

Troubleshooting your furnace might feel like an intimidating chore when your heat won’t start. But it doesn’t have to be like that.

There are a couple of fast, inexpensive fixes you can do on your own to skip a furnace repair call.

If your furnace won’t turn on, won’t stay on or won’t ignite, try the troubleshooting list below before contacting an HVAC professional.

If you find you need help from an expert and live in St. Louis, Morgner Inc. Air Conditioning & Heating can provide assistance to you. We work on most brands of heating systems.

If you’re ready for a new heating system, we also provide furnace replacement in St. Louis.

While you’re in touch with us, think about a regular furnace maintenance plan from Morgner Inc. Air Conditioning & Heating that could help you avoid problems in the future. We can tell you how regularly your furnace should be examined by one of our NATE-certified specialists.

Follow our easy guide below to get started on troubleshooting your furnace. Most of these steps don’t require mechanical know-how.

Steps for Furnace Troubleshooting

Check the Thermostat

To start, make sure your thermostat is signaling your furnace to turn on.

If you have a digital thermostat:

  • Change the batteries if the screen is blank. If the digital screen is jumbled, the thermostat may need to be replaced.
  • Make sure the switch is set to “heat” rather than “off” or “cool.”
  • Ensure the program is set to the right day and time and is set to “run.” If you’re having a hard time overriding the program, set the temperature by using the up/down arrows and press the “hold” button. This will force the furnace to ignite if thermostat programming is causing an issue.
  • Increase the temperature setting to 5 degrees warmer than the room temperature.
Digital Thermostat

If your furnace hasn’t turned on within several minutes, make sure it has power by toggling the fan switch from “auto” to “on.” If the fan doesn’t begin to run, your furnace might not have power.

If you have a smart thermostat—like one made by Nest, Ecobee, Lux, Honeywell or Bosch—troubleshooting is very model-specific. Take a look at the manufacturer’s website for help. If you still can’t get your Wi-Fi thermostat to work, contact us for assistance.

Lennox Smart Thermostat

Examine Breakers and Switches

Next, you will need to check if your breaker and furnace switch are on.

  • Look for your house’s main electrical panel. If you have no idea where it is, keep an eye out for a gray metal box in your basement, garage or closet.
  • Make sure your hands and feet are dry before touching the panel or breakers.
  • Look for the breaker labeled “furnace” or “heat,” and make sure it’s switched “on.” If the breaker has tripped, it will be in the middle or “off” position.
  • Using one hand, firmly switch the breaker to the “on” position. If the breaker immediately trips and pops back to “off,” don’t try to reset it and get in touch with a professional from Morgner Inc. Air Conditioning & Heating at 314-262-4541 right away.

It doesn’t matter how old your furnace is or what brand it is, it has at least one standard wall switch located on or close to it.

  • Make sure the switch is flipped up in the “on” position. If it was turned off, expect your furnace to take up to five minutes to start. (If you don’t know where to find your furnace, take a look at your basement, garage or utility closet. It could also be in a crawl space or attic.)

Replace Your Furnace’s Air Filter

When it comes to furnace problems, a grungy, clogged air filter is regularly the top offender.

If your filter is too dirty:

  • Your furnace won’t keep heating your home, or it could overheat from limited airflow.
  • Your energy bills could go up because your furnace is turning on more often.
  • Your furnace could break down prematurely because a dirty filter causes it to overwork.
  • Your furnace can lose power if an overly dirty filter causes the breaker to trip.

Depending on what type of furnace you use, your air filter will be inside the blower compartment of your furnace, an attached filter case or wall-mounted return air grille.

Replacing a furnace filter

To replace your filter:

  • Turn off your furnace.
  • Remove the filter and hold it up to the light. If you can’t see light through it, replace it.
  • Insert the new filter with the arrow pointing toward the furnace to avoid damage.

Flat filters should be replaced monthly, while pleated filters should 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 have to replace your filter more frequently.

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

Examine the Condensate Pan

Also known as drain pans, condensate pans hold water your furnace removes from the air.

If water is seeping out of your furnace or its pan has standing water in it, follow these steps.

  • If your pan has a drain (look for a PVC pipe), check that it isn’t full. If it needs to be drained, use a special pan-cleaning tablet you can purchase at home improvement or hardware stores.
  • If your pan has a pump, check the float switch. If the switch is stuck “up” with liquid in the pan, contact Morgner Inc. Air Conditioning & Heating at 314-262-4541, because you will possibly need a new pump.

Peek Inside Your Furnace

If malfunctions keep on happening, look inside your furnace’s plastic window to confirm the status of the blower motor. Depending on the model, the light could also be mounted on the outside of your furnace.

If you see anything except a steady, colored light or blinking green light, call Morgner Inc. Air Conditioning & Heating at 314-262-4541. Your furnace may be emitting an error code that requires professional service.

Clean the Flame Sensor

If your furnace tries to start but turns off without blowing heat, a dirty flame sensor could be at fault. When this happens, your furnace will make an attempt to ignite three times before a safety feature turns it off for about an hour.

If you feel comfortable with opening up your furnace, cleaning your flame sensor is something you can do on your own. Or, one of our HVAC specialists at Morgner Inc. Air Conditioning & Heating can do it for you.

If you want to clean the sensor yourself, you’ll need:

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

Next:

  • Disable the furnace’s power by using its wall switch or breaker. If your gas valve is not electric, you will need to shut off the gas as well.
  • Take off the furnace’s front panel and follow the wire to the flame sensor.
  • Unscrew the rod and use your sandpaper, steel wool or emery cloth to carefully rub the metal rod.
  • Wipe off the rod with a paper towel.
  • Remount the sensor.
  • Replace the furnace doors.
  • Turn the furnace’s power back on. It might proceed through a sequence of checks before proceeding with usual operation. If your furnace doesn’t start, the sensor may need to be replaced or something else might be wrong. If this happens, call Morgner Inc. Air Conditioning & Heating at 314-262-4541 for assistance.

Relight the Pilot Light

If you have an older furnace, the pilot light could be extinguished. To relight it, find the instructions on a label on your furnace, or follow these steps.

  • Find the switch on the bottom of your furnace labeled “pilot,” “on” and “off.”
  • Turn the switch to the “off” position.
  • Wait at least five minutes to avoid possibly sparking 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.

If you have followed the instructions twice and the pilot light still won’t light or stay lit, contact Morgner Inc. Air Conditioning & Heating at 314-262-4541.

Check Your Fuel Source

Try using another gas appliance. If it doesn’t work, your natural gas service could be turned off, or you could be out of propane.

Morgner Inc. Air Conditioning & Heating Can Help with Furnace Problems

Followed our troubleshooting guide but your furnace still won’t work?

Call us today at 314-262-4541 or use our online scheduler. We’ll come out and pinpoint the problem.

*Required fields