Furnace Not Heating in Pleasant Hill, CA

Furnace Not Heating in Pleasant Hill

A furnace that won't produce heat almost always comes down to one part, not a dead system: a cracked hot surface igniter, a flame sensor coated in carbon, a high-limit switch tripped by a choked filter, a control board that lost a relay, or a thermostat that dropped its call for heat. Pleasant Hill's older housing stock points straight at the front of that list.

Pleasant Hill sits inland in the Diablo Valley, where winter mornings drop into the mid-30s, so the heat actually gets worked here, unlike the milder coastal towns. A lot of our service area, Gregory Gardens, Poets Corner, and the tracts off Contra Costa Boulevard, is 1950s and 60s ranches running gas furnaces that are 20 to 30 years old. On equipment that age, the igniter and the control board are the parts that wear out first, and a cold snap is when a marginal one finally fails. The newer Hidden Lakes homes run multi-zone systems, where a no-heat call can also be a zoning-damper or zone-board issue.

The good news is that even on an old furnace, a no-heat fault is usually a contained repair. The igniter, sensor, or limit switch is a part-level fix. We diagnose what actually failed, and only when the heat exchanger or a stack of failures says otherwise do we put a replacement on the estimate.

Common causes

Cracked hot surface igniter. On the 20-to-30-year-old furnaces common in the flatland ranches, this is the most frequent no-light failure. The igniter cracks from years of heat cycling and stops glowing, so the burners never ignite. We meter it and replace it, $200 to $350.

Dirty flame sensor. If the furnace lights then shuts down after a few seconds, the flame sensor is carboned over and the board can't confirm flame, so it cuts the gas. Cleaning usually fixes it; a pitted sensor is $150 to $200 to replace.

Limit switch tripped by a dirty filter. Pleasant Hill ranches often run their filters through tight attic or crawl-space returns that don't get changed often. A clogged filter starves airflow, overheats the heat exchanger, and trips the high-limit. We confirm filter and airflow and check whether the limit reset or failed closed.

Worn control board on an aging furnace. After 20-plus years, the control board's heat relay can fail and stop sequencing the ignition. We test the board's outputs rather than condemning it on sight, since the board is one of the costlier furnace parts and is sometimes the point a 25-year-old unit isn't worth keeping.

Zone damper or zone board fault on Hidden Lakes systems. On the newer multi-zone homes, a stuck zone damper or a glitchy zone board can leave a room cold even while the furnace fires. We test the damper motors and zone panel to separate a distribution problem from a heat-production failure.

Failing gas valve. On older units the gas valve coil can weaken so it won't open reliably on a call for heat. We meter voltage at the valve to confirm whether it's the valve, the board feeding it, or a tripped safety upstream before quoting the part.

How we diagnose it

Confirm a real heat call reaches the control board before opening the burner compartment.
Run a full ignition sequence and note where it stops: inducer, igniter glow, gas valve, flame sensing.
Meter the igniter, flame sensor, and limit switch directly instead of swapping parts on a guess.
On multi-zone Hidden Lakes systems, test the zone dampers and zone panel to rule out a distribution fault.
Meter carbon monoxide and inspect the heat exchanger on every gas furnace, especially the 20-plus-year-old units.

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

Furnace Not Heating in Pleasant Hill: common questions

Do you cover Pleasant Hill, and can you come same day?

Yes, Pleasant Hill is well inside our service area, from Gregory Gardens to Hidden Lakes. We're based in San Ramon, and same-day is best-effort with no-heat calls prioritized. Call (925) 999-4095 and we'll give you an honest arrival window.

It gets genuinely cold here in winter. Should I repair or replace an old furnace?

Pleasant Hill's mid-30s mornings do mean you need reliable heat, and a no-heat fault is usually a $200-something repair even on an older unit. But if your furnace is 25-plus years with a cracked heat exchanger or a failing board, we'll run the replacement numbers on the estimate, and in this climate a heat pump often pencils out since it handles both the winter heat and the heavy summer cooling. The $75 diagnostic is credited toward any repair over $200.

My furnace won't light at all, not even a click. What's the first thing you check?

We start by confirming the thermostat is actually sending a heat call to the board, then watch the ignition sequence. No click and no glow usually means the igniter or the control board isn't getting or sending the signal. On a 20-plus-year-old Pleasant Hill furnace the cracked igniter is the leading suspect, but we meter it rather than assume.

Nearby and related

Furnace Not Heating near Pleasant Hill: Walnut Creek · Concord · Lafayette · Martinez .

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