HVAC
Furnace Repair in Union County & Central NJ
Furnace troubleshooting and repair for all makes and models, including no-heat calls.
When a furnace stops heating, shuts itself off, or starts making sounds it never made before, you need someone to find the actual cause rather than swap parts until something works. Furnace repair covers the ignition system, flame sensor, gas valve, inducer and blower motors, pressure and limit switches, control boards and thermostat wiring. At Vanguard, the technician who comes out is licensed and on our own staff, never a subcontractor. They test each stage of the heating sequence to pinpoint the failure, explain it in plain terms, and give you the repair price in writing before starting.
Common problems and how we handle them
Why is my furnace running but blowing cold air?
Start with the thermostat. With the fan set to On instead of Auto, the blower runs between heating cycles and the air feels cool. If the setting is right, the furnace may be shutting its burners down partway through a cycle. A clogged filter or blocked return can make it overheat until a safety limit cuts the flame, while the blower keeps running to cool the heat exchanger. A dirty flame sensor or a blocked condensate drain on a high-efficiency model can also stop the burners soon after they light.
Why does my furnace keep turning on and off?
Short cycling has a handful of common causes. A dirty flame sensor lets the burners light for a few seconds, then the control board shuts the gas off because it cannot confirm the flame. Restricted airflow can overheat the heat exchanger and trip the high limit switch again and again. Problems with the draft inducer or its pressure switch can make the furnace start, abort and retry. A thermostat mounted near a heat source can also misread the room. Each cause has a different fix, which is why testing comes before replacing parts.
What does the blinking light on my furnace mean?
Most modern furnaces have a control board with a small LED that flashes a fault code. A legend on the back of the door panel, or in the owner's manual, translates the pattern into a category such as a pressure switch fault, an open limit or failed ignition. Write down or photograph the pattern before cutting power, because turning the furnace off often clears it. The code tells a technician where to start looking, but it points to a circuit rather than a specific broken part.
Is a burning smell or loud noise from my furnace dangerous?
A dusty smell in the first few minutes of the season is usually dust burning off and fades on its own. A burning plastic or electrical smell that lingers, or a loud bang when the burners light, which can mean gas is building up before it ignites, is different: turn the furnace off and have it checked before using it again. A rotten egg smell can mean a gas leak, so leave the house without switching anything on or off and call your gas utility's emergency line or 911 from outside. If a carbon monoxide alarm sounds, get everyone outside and call 911.
How the job works
- We start with what you noticed: when the problem began, what the thermostat shows, any fault code flashing, and whether the furnace makes any attempt to start.
- The basics get confirmed first, including the thermostat signal, power at the furnace, filter condition, gas supply and, on high-efficiency units, the condensate drain and outdoor vent pipes.
- The furnace is run through its startup sequence while each stage is watched: inducer motor, pressure switch, igniter, gas valve, flame proving and blower.
- At the stage where it fails, meter readings such as voltage, flame sensor current and gas pressure confirm which part is at fault instead of guessing.
- Nothing is replaced until you have the diagnosis and a written repair price and have approved it.
- After the repair, the furnace runs through complete heating cycles while the safety controls are tested and the area around the unit is checked for carbon monoxide.
Cost of furnace repair
What a furnace repair costs depends on which part failed and how hard it is to reach. Cleaning a flame sensor or clearing a clogged condensate drain is a small job, while a control board, inducer motor or blower motor means a pricier part and more labor. Parts made only for your furnace's brand can cost more than universal replacements. Diagnosis comes first, and the repair price goes in writing for your approval before any work starts.
Why homeowners call Vanguard for furnace repair
- Licensed and insured. We work under NJ Master Plumber license NJMPL 13344 and HVACR license 19HC00609600, and every job is done by our own technicians, never a subcontractor.
- Upfront pricing, free estimates on most jobs. You approve a written price before work begins. No surprise line items when the job is finished.
- 4.9 stars across 556+ Google reviews. Read what customers say.
- Answered 24/7. Our phone is answered around the clock, including holidays.
Related HVAC services
Areas we serve
We provide furnace repair throughout Union, Middlesex, Somerset, and Essex counties, including:
Furnace Repair questions
Should I keep resetting my furnace if it shuts off?
Turning the power off and back on once is reasonable, since it clears a lockout and lets the furnace try again. If it locks out again, stop there. Furnaces shut down on purpose when a safety device detects overheating, flame rolling out of the burner area, or poor venting, and repeated resets can keep an unsafe condition running. Note any flashing code and call for service instead.
What is a cracked heat exchanger, and why does it matter?
The heat exchanger is the metal chamber that keeps burner exhaust separate from the air your blower sends through the house. Years of heating and cooling can crack it, and a crack can let combustion gases, including carbon monoxide, into that air. The furnace should stay off until the problem is resolved. Replacing just the heat exchanger is sometimes possible, but on an older furnace, replacing the whole unit is often more practical. Ask to see photos of the damage.
What can I check before a technician arrives?
Make sure the thermostat is set to Heat, the setpoint is above room temperature, and its batteries are fresh if it uses them. Check that the furnace service switch, which looks like a light switch near the unit, is on and the breaker has not tripped. Confirm the blower door panel is fully closed, because a safety switch keeps the furnace off when it is loose. On high-efficiency models, look outside to see whether snow or leaves are blocking the vent pipes.
Can I call for furnace repair at night or on a holiday?
Yes. Our phone at 908-577-5579 is answered 24/7, holidays included, so you can reach us when the heat quits overnight or during a holiday weekend. Have the fault code, the furnace brand from the rating plate and a short description of what it is doing ready when you call. That information helps the technician come prepared for the likely cause.
Ready to Get It Fixed?
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