When your furnace won’t start, doing your own furnace repair in Columbia, Mississippi, can feel pretty overwhelming.

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 several time-saving, inexpensive fixes you can do on your own to prevent 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 getting in touch with an HVAC professional.

If you find you need help from a heating and cooling pro and live in Columbia, Watts Electric & AC can provide assistance to you. We can repair most types of heating systems and also provide emergency furnace repair.

If you need a new heating system, we also do furnace installation.

While you’re chatting with us, consider a regular furnace maintenance plan that might help you avoid repairs in the future. We can tell you how often your furnace should be examined by one of our NATE-Certified professionals.

Follow our easy guide below to start troubleshooting your furnace. Most of these steps don’t require mechanical skills.

Furnace Repair Checklist

1. Check the Thermostat

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

Digital Thermostat

Replace 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 trouble overriding the program, set the temperature by using the up/down arrows and press the “hold” button. This will make the furnace to ignite if thermostat programming is causing trouble.

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

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 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. Check the manufacturer’s website for help. If you still can’t get your Wi-Fi thermostat to work, call us at 601-736-7362 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 aren’t sure 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.

Find 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 touch it and call a professional from Watts Electric & AC at 601-736-7362 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, expect your furnace to take up to five minutes to start. (If you don’t know where to find your furnace, look in 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 problems, a grungy, clogged air filter is frequently 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 increase because your furnace is turning on too often.
  • Your furnace could stop working prematurely because a dirty filter causes it to work harder.
  • Your furnace can be cut off from power if an overly dirty filter causes the breaker to trip.

Depending on what model of furnace you have, your air filter will be 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 hold it up to 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 once a month, while pleated filters should last about three months. You can also buy a washable filter that will last about 10 years. If you have children or pets, you may have to replace your filter more often.

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

4. Inspect the Condensate Pan

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

If water is leaking 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’s clear. 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 601-736-7362, because you will probably need a new pump.

5. Check for Furnace Error Codes

If malfunctions continue, peek inside your furnace’s plastic window to check the status of the blower motor. Depending on the model, the light could also be fixed on the outside of your furnace.

If you see anything else besides a steady, colored light or blinking green light, call us at 601-736-7362 for HVAC service. Your furnace may be emitting an error code that requires professional help.

6. Clean the Flame Sensor

If your furnace tries to start but turns off without distributing heat, a dirty flame sensor could be at fault. When this happens, your furnace will attempt to ignite 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 professionals 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:

  • Shut 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 lightly 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 series of checks before continuing usual operation. If your furnace doesn’t ignite, the sensor may need to be replaced or something else might be wrong. If this happens, call us at 601-736-7362 for heating and cooling repair assistance.

7. Relight the Pilot Light

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

  • Locate 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 starting a fire.
  • Turn the knob to “pilot.”
  • Press 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 601-736-7362 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 601-736-7362 or contact us online. We’ll come out and figure out the problem.

Request Service