HVAC Repair in Herndon, VA
Homes here need heat from October through April and cooling from June through September. If your system quits, tell us what it's doing and a licensed contractor who covers Fairfax County will get in touch.
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Eleven months of work for one system in Herndon
Your furnace and your AC in Herndon are almost never both off duty. Heat runs October through April. Cooling picks up in June and holds through September. That's 11 months a year one or the other is cycling on, with barely a break between them.
Winter nights averaging 28°F mean the burner is firing often and long to hold the house warm. Every start puts wear on the igniter. Summer afternoons near 86°F push the compressor hard for months straight, and that's when a weak capacitor or a low-on-refrigerant coil finally gives out. Storms add to the strain. The area has logged 10 winter storms and 387 damaging wind events over the past ten years, and statewide, 22% of homes lost power for at least a day in 2024. Most systems restart on their own once power is back, but one already worn down by months of heat or cold has less room to take a hard restart on top of it.
- 7 months
- October through April, your system heats
- 4 months
- June through September, it cools
- 28°F
- the average winter night it heats against
- 86°F
- the average summer afternoon it cools against
NOAA nClimDiv, 1991–2020 normals
A new furnace and air conditioner would cut about $160 a year off heating and cooling for a typical Fairfax County home.
Estimates for a typical Fairfax County home, compared with an older unit built to the previous federal minimum, from EIA household energy data, Virginia fuel prices and NOAA climate normals. Your home will differ.
Repair makes sense when one part has failed.
Replacement makes sense when the furnace's heat exchanger is cracked, the air conditioner's compressor has failed, or repairs keep coming.
Virginia requires HVAC contractors to hold a state license.
The license is issued to the contractor's business, not to each job it does. Virginia's Board for Contractors tests and records the company before it can legally take HVAC work, so the license tells you the business behind the repair has met the state's standard. Work under $1,000 falls outside that requirement, so a small repair can legally be done without a licensed contractor.
A heating and cooling repair is the kind of job that license requirement is built for. The contractor working on your system is the one the state tested and put on record, and that record covers the business doing the work rather than a separate check on this particular repair.
Sources: Virginia General Assembly · Virginia Department of Professional and Occupational Regulation
- Why is my heat not working?
- The most common cause is the igniter or flame sensor failing on a gas furnace, which stops it from lighting even though power and gas are getting to it. A tripped breaker or a switch on the furnace itself can also cut it off entirely. Check the thermostat is set to heat and above room temperature, and check the filter isn't so clogged it shut the system down on limit. With winter nights here averaging 28°F, a furnace that won't fire needs a contractor out quickly rather than waiting to see if it starts on its own.
- Why is my system running but not cooling the house?
- If air is moving but it isn't cold, the most likely cause is low refrigerant from a leak, a frozen evaporator coil, or a condenser outside that's blocked or caked with dirt. A dirty filter can also starve the system of airflow until the coil freezes over. Check the outdoor unit for leaves, grass clippings, or anything blocking the sides, and check the filter. If the coil has ice on it, shut the system off and let it thaw before a contractor looks at it, since running it iced up can damage the compressor.
- What can I check before calling for HVAC repair?
- Start with the thermostat. Check the batteries, the mode, and the set temperature. Then check the breaker panel for a tripped breaker, since a furnace, air handler, and outdoor condenser each run on their own circuit. Check the filter next, since a filter clogged with dust can cause a furnace to overheat and shut off or an air conditioner's coil to freeze. If the outdoor unit isn't running at all, check that nothing is blocking it and that the disconnect switch nearby is pushed in. If you've checked these and the system still isn't working, a contractor will need to diagnose it further.