Every time your thermostat calls for heat, the furnace works through a fixed checklist. The inducer motor starts and proves draft by closing a pressure switch, the hot surface igniter heats up, the gas valve opens, the burners light, and the flame sensor confirms there is fire. Only after all of that does the blower begin sending warm air into the house. Finding the step that fails is most of the job. Around Gilroy, CA, the usual failure points are an oxide-coated flame sensor, an igniter cracked by years of heating and cooling, a pressure switch that stays open because of a weak inducer or a clogged condensate trap on a high-efficiency unit, and control boards with burned relays. Each one halts the startup, and from the hallway they all look alike.
Our experienced technicians diagnose a furnace the way it operates, in order, with a meter at every step. That means igniter resistance, microamp flame signal, pressure switch operation under actual inducer draft, gas valve voltage, and blower and capacitor condition. Safety checks are never optional on a gas appliance: heat exchanger inspection, leak testing on the gas connections, and flue draft verification, since a hazard rarely shows itself at the thermostat. We finish by checking temperature rise against the data plate, making sure the burner and blower are matched the way the manufacturer designed them to.
We work on natural gas, propane, and electric furnaces from every major brand, both conventional 80 percent units and condensing high-efficiency models with their traps, drains, and dual pressure switches. The truck stock covers the parts that actually fail: igniters, flame sensors, pressure switches, capacitors, inducer assemblies, and blower motors, so most no-heat calls end with heat the same visit. For furnace repair anywhere in Gilroy, call (408) 694-4630 and we will get the burners lit today.
For air conditioning breakdowns, see AC Repair in Gilroy.
How Much Does Furnace Repair Cost in Gilroy?
Most furnace repairs in Gilroy cost between $150 and $600. The price depends on which part failed and how old the furnace is. You'll get a written, upfront price from Gilroy HVAC after we diagnose the problem.
| Repair | Typical cost | What it usually means |
|---|---|---|
| Flame sensor cleaning or replacementBurners light but cut out almost immediately | $80–$250 | Burners light but cut out almost immediately |
| Hot surface igniter replacementNo ignition; one of the most common winter failures | $150–$400 | Furnace clicks and tries to start but never lights |
| Draft inducer motorLoud humming or grinding at startup, then lockout | $400–$1,000 | Startup fan fails, furnace won't fire |
| Blower motorNo airflow, or the blower runs nonstop | $400–$1,500 | Burners run but little or no air comes out of the vents |
| Control boardErratic behavior, error codes, or no response at all | $300–$700 | Erratic behavior, error codes, or no response at all |
| Gas valve replacementValve fails to open, so the furnace never lights | $250–$700 | Igniter glows but gas never flows to the burners |
These are common price ranges, not quotes. We confirm the exact price after diagnosing your system.
Factors That Change the Price
- Furnace age and type, because 90%+ efficiency models have more specialized parts
- Whether a cracked heat exchanger is found, which usually means replacement rather than repair
- Timing, such as a no-heat call on a cold night versus a scheduled repair
- Access to the furnace in attics, closets, or crawlspaces
For older furnaces facing a big repair, we'll show you what replacement would cost too, so you can compare. Call (408) 694-4630 for a quote.
Warning Signs for Furnace Repair
Catching these issues early helps you avoid costly problems and protect your property. These are the signals our technicians see most often when a problem is underway:
- A flame that burns soft and yellow rather than steady blue
- Frequent on-off cycling that never reaches the thermostat setting
- A fan that keeps running while the registers blow cool air
- Booming or banging at light-off from delayed ignition
- Burners light, run a few seconds, then shut down repeatedly
- Rust streaks, soot, or water around the cabinet or flue
- Clicking and a glowing igniter with no burner flame
- Grinding or high-pitched squeals from the blower
Don't Wait for a Total Failure
Left unchecked, even a small fault or temperature swing often signals a system working its way toward a breakdown. If you notice any of these signs, contact Gilroy HVAC at (408) 694-4630 for a prompt inspection.
Furnace Repair FAQ
Why Professional Furnace Repair Matters
Gas, open flame, high voltage, and a flue share one cabinet in a furnace, and the most dangerous failure is the one you cannot see: a damaged heat exchanger that lets combustion gases into the air the blower sends through your home. Every morning that delayed ignition keeps booming at startup, that exchanger takes more stress. The diagnostic side has its own pitfalls. When a furnace trips its high limit, the switch itself may be bad, or the furnace may be protecting itself from a clogged filter or a failing blower. Swapping the switch in that second case removes a safety device and leaves the actual problem in place.
At Gilroy HVAC, no symptom gets treated in isolation. A meter tells us the flame signal, so we never condemn a good sensor while the real culprit, a cracked igniter or a weak gas valve, keeps causing trouble. We confirm draft at both the pressure switch and the flue, measure temperature rise against the data plate to flag airflow problems early, and test the gas side with a leak detector, not a guess. When we are done, the furnace has proven itself safe and correct through a full cycle, and if it is nearing the end of its useful life, you will get an honest assessment.
Our Furnace Repair Process
Every visit follows a step-by-step method refined over years of hands-on experience. Here's a look at each step our Gilroy HVAC team takes:
Sequence Diagnosis
We watch the furnace's startup sequence and measure at every stage: inducer draft, pressure switch, igniter resistance, flame signal, and gas valve operation, to find exactly where it breaks.
Combustion Safety Check
On every visit, we inspect the heat exchanger, leak-test the gas connections, and confirm the flue is drafting. No furnace repair is complete until the unit is proven safe.
Expert Repair
Igniters, flame sensors, pressure switches, capacitors, and motors ride on the truck, so most furnaces are lit and heating again before we pack up.
Final Cycle Testing
We run complete cycles, measure temperature rise against the data plate, confirm clean ignition without booming, and verify every limit and safety control before we leave.
Maintenance Tips for Furnace Repair
A few simple habits now, like regular filter changes and seasonal tune-ups, can add years to your system's life. Here are our expert recommendations:
- Listen at light-off; clean ignition is quiet, and booming means the burners need service
- Avoid packing the utility room, because burners need open space for combustion air
- Put a carbon monoxide detector on every level and test them monthly
- Put in a fresh filter monthly through the heating season, the cheapest protection your furnace can get
- Schedule service each fall to catch worn igniters and dirty sensors before cold weather arrives
- Store laundry supplies, especially chlorine products, well away from the furnace closet
- Keep the condensate trap and drain clear on high-efficiency units to prevent lockouts
Should You DIY or Call a Pro?
A homeowner can swap a filter with ease, but diagnosing capacitors, refrigerant charge, control boards, and error codes calls for the equipment and know-how only a pro brings. Consider the following comparison:
| Factor | DIY Attempt | Professional Service |
|---|---|---|
| Heat Exchanger | Cracks invisible from the outside | Examined as standard on each call |
| Ignition Faults | Parts swapped against a code list | Igniter, sensor, and valve each metered |
| Gas Connections | Small leaks missed entirely | Every fitting checked with a detector |
| Limit Trips | Safety switch bypassed or swapped | Root cause of overheating corrected |
| Airflow Match | Airflow assumed, not measured | Blower tuned to the rated rise |
| Final Check | One good start and done | Clean, safe operation verified over full cycles |
Talk to a Furnace Repair Expert
Don't let a failing system get worse. Call Gilroy HVAC now for prompt, professional service.
Call (408) 694-4630 NowAreas We Serve for Furnace Repair
We serve Gilroy and its neighboring communities for furnace repair, from quick same-day repairs to planned installs.