Gas furnace repair in San Mateo County
No heat? Let's get the furnace running.
We diagnose gas furnaces that won't start, short-cycle, blow cold air or make noises, and we repair the part that failed. The visit checks the gas, the venting and the flame. And no, a rule about gas furnaces doesn't mean you have to rip out a working one.
What a furnace repair visit covers
A gas furnace is a chain: thermostat, ignition, flame, heat exchanger, blower and vent. When it stops heating, one link has failed. The visit is about finding which one.
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Safety first
Before we touch anything we check for gas odor, the venting and the flame. A furnace that is unsafe stays off until it is fixed.
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We follow the sequence
We watch it try to start: thermostat call, inducer, ignitor, gas valve, flame sensor, then the blower. Where the sequence stops is where the fault is.
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We repair the part that failed
An ignitor, a flame sensor, a blower motor or capacitor, a pressure switch, a control board: the repair goes at the cause.
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We run a full heat cycle
The furnace runs through a complete cycle before we leave, with temperature rise, flame and venting checked again.
Why has my gas furnace stopped heating?
Most of what we see comes down to a handful of causes:
- A dirty flame sensor or a worn ignitor, so the furnace tries to light and shuts itself off.
- A failed blower motor or capacitor: the furnace fires but little or no warm air reaches the rooms, or the blower hums and won't turn.
- A clogged filter that chokes the airflow until the limit switch shuts the burners off to protect the furnace.
- A blocked vent or condensate drain on a high-efficiency furnace, which trips a safety switch.
- A thermostat that has lost power, or a control board that has failed.
A rattle, a squeal or a bang on start-up is worth a call. So is a yellow, floppy flame, soot, or a furnace that cycles on and off every few minutes.
When is a furnace problem a safety problem?
If you smell gas, leave the house and call your gas utility from outside. If a carbon monoxide alarm sounds, get everyone outside and into fresh air, and don't relight the furnace until it has been inspected.
A cracked heat exchanger, a blocked vent or a leaking gas connection won't always announce themselves. That is why a repair visit looks at them, and why a yearly tune-up is worth having.
Will I be forced to remove my working gas furnace?
No. The Bay Area Air District's zero-NOx rules for furnaces and water heaters apply when existing equipment burns out and is replaced. They do not force anyone to remove working equipment.
So the rule matters only on a burnout replacement, and a repair doesn't trigger it. The furnace rule has a 2029 compliance date and is still under review by a working group, so even that date may move.
Source: Bay Area Air Quality Management District, Rules 9-4 and 9-6 Building Appliances. Rules and programs change: last checked 2026-10-17.
Furnace not heating?
Call and tell us what it's doing, or book a visit online.
Is it worth repairing an older furnace?
If the failed part is an ignitor, sensor, motor or switch, repair usually makes sense. If the heat exchanger has cracked, repairs keep recurring or the furnace is well past its years, it is worth pricing a replacement.
When you do replace, you can choose between a new gas furnace and a heat pump in many places. We'll go through the choice with you.
Tell us what it's doing. We'll take it from there.
Call and describe the problem: the noise, the smell, the room that never warms up. Or book a visit online.
