It's the first cold night and the furnace just blows cool air, or it kicks on, runs two minutes, and shuts off again. Novus Mechanical repairs gas furnaces across Freehold and Monmouth County, and every call starts with a real, NCI-certified diagnosis instead of a guess. A furnace is a gas appliance. That changes how careful the work has to be.
Plenty of companies show up, swap the cheapest part they can name, and hand you a bill. The same fault comes back in a week and you pay again. Worse, a misdiagnosed furnace can hide a real safety problem.
We measure first, checking ignition, the flame sensor, the gas side, airflow, and the safety controls before we tell you what's wrong. If you're weighing your full heating options, our heating services overview covers everything on the warm side of the house.
The most common furnace problems are no heat at all, short-cycling, a blower that will not shut off, and a bang on ignition, and most trace back to one of a handful of failures we see every Freehold winter.
No heat at all. The furnace won't fire, or it fires and quits. Usual suspects are a dirty flame sensor, a failed hot-surface igniter, a tripped safety switch, or a clogged filter choking airflow. A couple you can rule out at home. The rest need a real look.
It short-cycles. The furnace runs a short burst, shuts down, and repeats. That on-off-on pattern usually means it's overheating and tripping its high-limit switch, often from a dirty filter, blocked vents, or a bad flame sensor. Short-cycling burns out parts fast, so catch it early.
The blower won't stop. The fan runs nonstop even when the burner is off, usually a stuck limit switch or a control-board fault. The heat is gone but the fan keeps pushing room-temperature air, which feels like a draft.
A bang or boom on ignition. A loud "whoomp" when the burner lights is delayed ignition: gas builds up a beat too long, then lights all at once. On a gas furnace that's not a wait-and-see. It points to dirty burners, a weak igniter, or a gas-pressure issue, and it gets checked the same visit.
| Symptom | Likely cause | What Novus measures |
|---|---|---|
| No heat at all | Dirty flame sensor, failed igniter, tripped safety switch, or a clogged filter | Flame sensor reading, ignition sequence, safety switch, airflow |
| Short-cycles: runs a minute, shuts off, repeats | Overheating trips the high-limit switch, often from a dirty filter or blocked vents | Static pressure, filter condition, supply and return airflow |
| Blower runs nonstop, no heat | Stuck limit switch or a control-board fault | Control board sequence, limit switch operation |
| Bang or boom on ignition | Delayed ignition from dirty burners, a weak igniter, or gas pressure | Burner condition, igniter output, gas pressure |
| Pilot or igniter will not stay lit | Failing thermocouple on pilot models, or a cracked hot-surface igniter | Thermocouple millivolt reading, igniter continuity |
A furnace usually will not ignite because the igniter or the pilot's thermocouple has failed, not because the whole unit is dying. Older furnaces use a standing pilot light, newer ones a hot-surface igniter that glows red-hot to light the burners. A pilot that won't stay lit usually means a dirty or failing thermocouple, the safety part that proves the flame before gas keeps flowing. A hot-surface igniter cracks with age and heat cycling, and once it cracks it stops glowing. Either way the burners never light and you get cold air.
Novus repairs pilot, thermocouple, and hot-surface igniter faults on gas furnaces across Freehold and Monmouth County. Because it's a gas appliance, we don't just drop the part in and leave. We confirm the furnace lights clean, holds flame, and vents right. If your heating side is really a heat pump, our heat pump repair page covers that instead.
A dirty flame sensor cannot sense the burner flame, so the control board shuts the gas off and the furnace locks itself out, and that is one of the most common no-heat calls there is, and one of the cheapest to fix. The flame sensor is a thin metal rod in the burner flame, and its only job is to confirm the burner lit. When it gets coated in carbon, the control board can no longer trust it, so it shuts things down. That's the safety system doing its job, not failing. Cleaning or replacing the sensor brings the heat back.
But on a gas furnace the part that failed is never the whole story. We test combustion and the safety chain as part of every repair: checking the heat exchanger for cracks, confirming the furnace vents properly, and watching for carbon monoxide risk. The U.S. EPA warns that a cracked heat exchanger can push carbon monoxide into the house, and you can't see or smell it. Our technicians hold NCI System Performance (#25-142-01) and Air Balancer (#25-143-01) certifications from the National Comfort Institute, plus EPA certification (#P165BDDE28EAD0701). That's why we test the whole combustion side, beyond the part that quit. A clean MeasureQuick system check-up catches many of these faults before the cold night they fail on.
Repair almost always wins on a furnace under about 15 years old with a routine part failure, and replacement wins once it passes 15 years, cracks a heat exchanger, or needs a repair that eats a big share of a new unit's cost. A 12-year-old unit with a bad igniter is an easy repair. A 20-year-old unit with a cracked heat exchanger rarely pays back the money you pour into it.
Replacement usually makes more sense once:
If the furnace is under about 15 years old and the repair is a reasonable share of a new unit, repair almost always wins. Once it passes 15 years, breaks down often, or shows a cracked heat exchanger, replacement makes more sense for both your wallet and your safety. Per the U.S. Department of Energy, today's high-efficiency furnaces waste far less fuel than the builder-grade units common in older Monmouth County homes. We run the numbers with you straight, and our furnace installation and replacement page walks through that side. We'd rather lose the sale than push a repair on a furnace that's done.
Novus Mechanical has served NJ homeowners since 2016 and holds a 5.0 average across 44 Google reviews. We're fully insured, with commercial liability and workers' comp. Financing is available if a repair turns into a replacement. Our techs are on site Monday through Friday, 8 to 6, and you can reach our team to book any time. Year-round furnace care is the core of what a maintenance plan covers.
No heat tonight? Schedule My Appointment or call (848) 288-1133.
We measure your home, explain what we find, and hand you one clear price. Book a consultation in Freehold or Monmouth County.
