Furnace Not Heating in Menlo Park, CA

Furnace Not Heating in Menlo Park

A furnace that won't make heat is almost always one broken part in a sequence, not a dead system. The thermostat calls, the inducer spins, the igniter glows, the gas valve opens, and the flame sensor confirms the burn. Break any single step and heat stops. The repair is usually a component, not a replacement.

Menlo Park runs mild summers and light winters, so furnaces here tend to be modestly sized and lightly loaded. That's good for longevity, but it means the failures we see are mostly age-related: cracked igniters, dirty flame sensors, and worn parts on units that have quietly run for fifteen-plus years. A fair number of the older homes still have original heating equipment that's well past service life.

Because the climate is forgiving, a no-heat furnace here is rarely an emergency. It's a good moment to do the safety check properly. Older units are at the age where heat exchangers start to crack, and that's a CO question we settle on the spot with a meter.

Common causes

Cracked hot surface igniter. Even lightly loaded furnaces lose igniters to thermal cycling over the years. The igniter won't glow, the burners don't light, and you get cold air or nothing. We test resistance, confirm the crack, and replace it. The part cost is on your written estimate.

Flame sensor carbon buildup. A furnace that lights and then quits within seconds usually has a dirty flame sensor. The board loses the flame signal and shuts gas off as a safety. Cleaning fixes it most of the time. If the sensor is worn out, replacing it is a small part we'll price first.

Limit switch tripped by a clogged filter. In the older homes here, a long-neglected filter restricts airflow and overheats the furnace, tripping the high-limit. We replace the filter, check static pressure, and confirm the limit resets. If the duct system is the bottleneck we note it on the estimate.

Aging control board. On units that have run two decades in a mild climate, the control board can develop intermittent faults, no ignition some cycles, normal others. We meter the board's outputs through a cycle to confirm before condemning it, since a loose connection can look the same.

Gas valve not opening. If the igniter glows and the inducer runs but the burners stay dark, the gas valve may not be opening. We check inlet pressure and the control signal before replacing it, because a board or wiring fault can mimic a failed valve.

Cracked heat exchanger on end-of-life units. Many original furnaces in the older neighborhoods are at the age where the heat exchanger cracks. That's a carbon monoxide risk, not a routine repair. We show you the crack on camera, and if CO is unsafe we shut the unit down and document it before leaving.

How we diagnose it

Confirm the thermostat is sending the heat call and the board is powered.
Run the full ignition sequence to find exactly where heat stops.
Pull and inspect the filter, then measure static pressure for airflow-driven limit trips in older homes.
Meter the control board through a cycle to catch intermittent board faults.
Test CO and inspect the heat exchanger on every gas furnace, especially original units past service life.

$75 diagnostic, credited toward any repair over $200. You get a written quote before any work begins.

Furnace Not Heating in Menlo Park: common questions

Will you come to Menlo Park, or is that out of range?

We cover the Peninsula from our San Ramon base, Menlo Park included. Same-day depends on the day's routing and is best effort, not guaranteed, so we'll quote you an honest arrival window when you call.

My old furnace failed. Should I just replace it?

Worth weighing. If your unit is past 15 years with a real failure, a heat pump conversion may be the smarter move, and the mild Menlo Park climate suits a smaller, efficient heat pump well. There's also a regulatory shift coming on new gas furnace installs in this region, so we'll factor that into the math at the estimate, no pressure.

Furnace turns on but only blows cool air. Why?

The burners aren't lighting or aren't staying lit while the blower still moves air. That's typically a cracked igniter, a fouled flame sensor, or a gas valve issue, all diagnosable parts. We watch a full cycle to pin down which one.

Nearby and related

Furnace Not Heating near Menlo Park: Palo Alto · Los Altos .

This is usually a furnace repair in Menlo Park job. See our furnace repair overview or the Menlo Park service area.