Furnace Repair in Manassas, VA

HVAC man working on a furnace

When your heater won’t work, doing your own furnace repair in Manassas, VA, can seem overwhelming.

There are a few quick, inexpensive fixes you can take on yourself to skip a HVAC service bill.

If your furnace doesn’t turn on, won’t run consistently or won’t light, check the troubleshooting checklist below in advance of calling an HVAC expert.

If you discover you need assistance from a heating and cooling pro and live in Manassas, Woody's Sudden Service Inc can assist you. We have the ability to repair most types of HVAC systems.

CALL NOW 703-278-2036

If you’re ready for a new heater, we also offer furnace installation.

While you’re in touch with our team, consider an annual furnace maintenance plan from Woody's Sudden Service Inc that could help you avoid problems down the line. Our team can tell you how often your furnace needs to be checked by one of our NATE-Certified professionals.

Go through our straightforward guide as demonstrated to start troubleshooting your furnace. A great deal of these steps don’t require mechanical know-how to complete your furnace repair.

Furnace Repair Checklist

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1. Check the Thermostat

First, make certain that your thermostat is instructing your heat to start.

Digital Thermostat

  • Change the batteries if the display is not displaying anything. If the digital screen is messed up, the thermostat could need to be changed.
  • Make certain that the switch is switched to “heat” instead of “off” or “cool.”
  • Ensure the program is displaying the appropriate day and time and is scheduled to “run.” If you’re having trouble overriding the setting, set the temperature with the up/down arrows and using the “hold” button. This will cause the furnace to ignite if thermostat is causing a problem.
  • Set the temperature setting to 5 degrees hotter than what the room temperature currently is.

If your heating hasn’t kicked on within several minutes, make sure it has juice by changing the fan switch from “auto” to “on.” If the fan doesn’t operate, your heater could be without power.

Smart Thermostat

If you use a smart thermostat—for example one manufactured by Nest, Ecobee, Lux, Honeywell or Bosch—troubleshooting will be determined by the model you have. Refer to the manufacturer’s website for help. If you still can’t get your Wi-Fi thermostat to function, reach us at 703-278-2036 for heating and cooling service.

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2. Inspect Breakers and Switches

Next, verify your breaker and furnace switch are on.

  • Find your main electrical panel. If you aren’t sure where it is, search for a silver metal box in your basement, garage or closet.
  • Make certain that your hands and feet are dry before using the panel or breakers.
  • Find the breaker titled “furnace” or “heat,” and double-check it’s reading “on.” If the breaker has tripped, it will be in the middle or “off” area.
  • Moving one hand, steadily turn 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 Woody's Sudden Service Inc at 703-278-2036 right away.

No matter your furnace’s age or brand, it has at minimum one ordinary wall switch installed on or near it.

  • Make sure the lever is flipped up in the “on” spot. If it was turned off, anticipate your furnace could take up to five minutes to turn on. (If you’re unaware of where to find your furnace, look in your basement, garage or utility closet. It may also be in a crawl space or attic.)
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3. Put in a New Air Filter

When it comes to furnace issues, a grungy, blocked air filter is frequently the top culprit.

If your filter is too grungy:

  • Your heat won’t keep heating your home, or it may get too hot from restricted airflow.
  • Your heating bills might increase because your heater is switching on more often.
  • Your heater could stop working sooner than it should due to the fact a dirty filter forces it to overwork.
  • Your heater can be disconnected from power if an overly dirty filter causes the breaker to trip.

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

To put in a new filter:

  • Cut the power to your heating system.
  • Pull out the filter and angle it toward the light. If you can’t notice light through it, replace it.
  • Install the new filter with the arrow pointing toward the heating system to avoid damage.

Flat filters ought to be replaced once a month, while pleated filters should last about three months. If you have children or pets, you may have to replace your filter more often.

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

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4. Check the Condensate Pan

Also known as drain pans, condensate pans capture moisture your heating system pulls from the air.

If moisture is dripping from your heater or its pan is overflowing, try these recommendations.

  • If your pan includes a drain (look for a PVC pipe), check that it isn’t clogged. If it requires draining, drop in a special pan-cleaning tablet you can purchase at home improvement or hardware stores.
  • If your pan uses a pump, take a look at the float switch. If the switch can’t be moved from the “up” position with standing water in the pan, contact us at 703-278-2036, because you will likely need a new pump.
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5. Check for Heater Error Codes

If faults persist, take a look inside your furnace’s plastic window to confirm the blower motor’s status. Dependent on the model, the light could also be mounted on the exterior of your heater.

If you see anything other than a solid, colored light or blinking green light, contact us at 703-278-2036 for HVAC service. Your furnace could be giving an error code that needs professional help.

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6. Scrub the Flame Sensor

If your heating system attempts to run but switches off without blowing warmth, a filthy flame sensor can be at fault. When this takes place, your heating system will attempt to ignite three times before a safety device shuts it down for approximately an hour.

If you feel okay with removing the panels from your heating system, cleaning your flame sensor is something you are able to do yourself. Or, one of our heating service professionals is able to do it for you.

If you want to clean the sensor on your own, you require:

  • A 1/4” hex screwdriver or wrench
  • Portion of light grit sandpaper, steel wool or emery cloth
  • An unused paper towel


  • Disable the heater’s power through its wall switch or breaker. If your gas valve isn’t electric, you will need to turn off the gas in addition.
  • 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 scrub the metal rod.
  • Clear the rod with a paper towel.
  • Remount the sensor.
  • Secure the furnace doors.
  • Turn the furnace’s power back on. It could run through a sequence of examinations before resuming usual heating. If your furnace doesn’t ignite, the sensor may require replacement or something else could be creating an issue. If this happens, contact us at 703-278-2036 for heating and cooling repair support.
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7. Relight the Pilot Light

If you are using an outdated heating system, the pilot light could be turned off. To relight it, find the guide on a sticker on your furnace, or try these guidelines.

  • Find the toggle below your furnace labeled “pilot,” “on” and “off.”
  • Push the switch to the “off” position.
  • Take a break for at least five minutes to prevent starting a fire.
  • Turn the dial to “pilot.”
  • Press the “reset” switch as you move the flame of a long lighter to the pilot light opening.
  • Let go of the “reset” lever once the pilot light is ignited.
  • If you have used the list twice and the pilot light still won’t light or keep burning, contact us at 703-278-2036 for furnace service.

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Double-Check Your Fuel Supply

Try using a second gas appliance. If it doesn’t function, your natural gas service might be shut off, or you may have run out of propane.

We Can Assist With Furnace Servicing

Used our troubleshooting checklist but your furnace still doesn’t run?

Call us right away at 703-278-2036 or contact us online. We’ll make a call at your house and figure out the trouble.


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