When your furnace won’t start, doing your own furnace repair in Shamokin and Sunbury, Pennsylvania, can feel pretty overwhelming.

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

There are a number of speedy, reasonable fixes you can do on your own to avoid 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 calling an HVAC professional.

If you find you need help from a heating and cooling pro and live in Shamokin and Sunbury, LTS Plumbing & Heating Inc. can help you. We can repair most makes of heating systems and also provide emergency furnace repair.

If you’re ready for a new heating system, we also provide furnace installation.

While you’re in touch with us, consider an annual furnace maintenance plan that may help you avoid breakdowns in the future. We can tell you how frequently your furnace should be examined by one of our certified professionals.

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

Furnace Repair Checklist

1. Check the Thermostat

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

Digital Thermostat

Swap out 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 appropriate 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 turn on if thermostat programming is causing an issue.

Increase the temperature setting to 5 degrees warmer than the room temperature.

If your furnace hasn’t started 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.

Smart Thermostat

If you have a smart thermostat—like one made by Nest, Ecobee, Lux, Honeywell or Bosch—troubleshooting is very model-specific. Refer to the manufacturer’s website for help. If you still can’t get your Wi-Fi thermostat to work, call us at 570-648-0748 for heating and cooling service.

2. 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 don’t know 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.

Locate 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 call a professional from LTS Plumbing & Heating Inc. at 570-648-0748 right away.

Regardless of your furnace’s age or brand, it has at least one standard wall switch located on or near it.

Make sure the switch is flipped up in the “on” position. If it was turned off, it could take your furnace up to five minutes to turn on. (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.)

3. Replace the Air Filter

When it comes to furnace breakdown, a filthy, clogged air filter is regularly the top culprit.

If your filter is too dirty:

  • Your furnace won’t keep heating your home, or it could overheat from reduced airflow.
  • Your energy bills could go up because your furnace is turning on more often.
  • Your furnace could stop working prematurely because a dirty filter causes it to overwork.
  • Your furnace can be disconnected from power if an extremely dirty filter causes the breaker to trip.

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

To replace your filter:

  1. Turn off your furnace.
  2. Pull out the filter and tilt it toward the light. If you can’t see light through it, get a new one.
  3. Put in 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 put in a new filter more often.

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

4. Inspect the Condensate Pan

Otherwise known as drain pans, condensate pans catch water your furnace pulls from the air.

If water is dripping 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 buy at home improvement or hardware stores.
  • If your pan contains a pump, inspect the float switch. If the switch is stuck “up” with liquid in the pan, contact us at 570-648-0748, because you will likely need a new pump.

5. Check for Furnace Error Codes

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

If you see anything else besides a steady, colored light or blinking green light, call us at 570-648-0748 for HVAC service. Your furnace may be emitting an error code that is calling for professional service.

6. Clean the Flame Sensor

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

If you feel comfortable with opening up your furnace, cleaning your flame sensor is something you can do by yourself. Or, one of our heating service experts 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:

  • Turn off 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.
  • Lift 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 may run through a set of checks before proceeding with normal operation. If your furnace doesn’t ignite, the sensor may need to be replaced or something else could be wrong. If this happens, contact us at 570-648-0748 for heating and cooling repair assistance.

7. 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.”
  • Push 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, call us at 570-648-0748 for furnace service.

Check Your Fuel Source

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

We Can Help with HVAC Repair

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

Call us today at 570-648-0748 or contact us online. We’ll come out and figure out the problem.

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