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

Fixing your furnace might feel like an intimidating job when your heat won’t power on. But it doesn’t have to be like that.

There are a number of fast, reasonable fixes you can do yourself 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 getting in touch with an HVAC professional.

If you find you need help from a heating and cooling professional and live in Marshalltown, B & G HVAC can assist you. We can repair most brands of heating systems and also provide emergency furnace repair.

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

While you’re talking with us, think over an annual furnace maintenance plan that could help you avoid problems in the future. We can tell you how often your furnace should be examined by one of our NATE-Certified professionals.

Go through our easy guide below to get to work on troubleshooting your furnace. Most of these steps don’t require mechanical abilities.

Furnace Repair Checklist

1. Check the Thermostat

To begin, make sure your thermostat is telling your furnace to start.

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” instead of “off” or “cool.”

Ensure the program is displaying the right day and time and is set to “run.” If you’re having problems 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 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 start, 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 641-316-3360 for heating and cooling service.

2. Examine Breakers and Switches

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

Locate your house’s main electrical panel. If you aren’t sure where it is, search 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 touch it and contact a professional from B & G HVAC at 641-316-3360 right away.

No matter 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 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 to blame.

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 increase because your furnace is turning on more than it should.
  • Your furnace could fail too soon because a dirty filter causes it to overwork.
  • Your furnace can be disconnected from power if an excessively dirty filter causes the breaker to trip.

Depending on what make of furnace you own, 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. Remove the filter and tilt it toward the light. If you can’t see light through it, replace it.
  3. Install 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 buy a washable filter that will last about 10 years. If you have children or pets, you may have to replace your filter sooner.

To make the process easier 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

Otherwise known as drain pans, condensate pans catch water your furnace draws 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’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 has a pump, inspect the float switch. If the switch is stuck “up” with standing water in the pan, contact us at 641-316-3360, because you will probably need a new pump.

5. Check for Furnace Error Codes

If malfunctions continue, take a look inside your furnace’s plastic window to verify 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 other than a steady, colored light or blinking green light, call us at 641-316-3360 for HVAC service. Your furnace may be giving an error code that is calling for professional assistance.

6. Clean the Flame Sensor

If your furnace tries to start but turns off without distributing heat, a dirty flame sensor could be to blame. When this occurs, 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:

  • 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.
  • 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 gently 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 could proceed through a series 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 641-316-3360 for heating and cooling repair assistance.

7. Relight the Pilot Light

If you own 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.

  • Look for 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.”
  • 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, contact us at 641-316-3360 for furnace service.

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.

We Can Help with HVAC Repair

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

Call us today at 641-316-3360 or contact us online. We’ll come out and figure out the problem.

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