Furnace Not Heating in Martinez

Furnace Not Heating in Martinez

No heat from a gas furnace is rarely a dead system. The furnace lights in a fixed order. The inducer has to draft, the igniter has to glow, the gas valve has to open, and the flame sensor has to prove the burn before the blower joins in. A single failed part anywhere in that chain stops the whole thing, and most of the time it's a cheap component rather than the furnace.

A lot of Martinez homes are older tract houses running conventional ducted gas furnaces that are now well into replacement age, so we see classic wear failures: cracked igniters, worn draft inducers, and tired control boards. Some of the older homes closer to the historic core have little or no ductwork and rely on wall heaters or older gas furnaces, where no-heat means a different diagnosis entirely.

Sitting on the Carquinez Strait, Martinez winters are cool but not severe, so a furnace that quits usually isn't an emergency. What it is worth is a proper safety check. Older furnaces here are the right age to start cracking heat exchangers, and a CO test takes us a few minutes.

Common causes

Cracked hot surface igniter. On the older tract furnaces, this is the most common no-heat call. The igniter cracks from years of heat cycles and the burners never light, though the blower may still run. We confirm with a resistance test and replace it, with the exact part cost on your written estimate.

Limit switch tripped by a dirty filter. A neglected filter on an older furnace chokes airflow, overheats the unit, and trips the high-limit switch, which kills the burners. We swap the filter, check static pressure, and confirm the limit resets. On these decades-old systems we also look at whether the ductwork is part of the airflow problem.

Flame sensor carbon buildup. The furnace lights, then shuts down a few seconds later. The flame sensor is fouled and the board stops seeing flame. Cleaning the rod usually solves it. A worn sensor that needs replacing is a small part we'll price before doing it.

Worn draft inducer motor. On furnaces past about a decade, the inducer that vents combustion gases wears out. If the pressure switch doesn't see proper draft, the furnace won't fire at all as a safety lockout. We confirm the inducer and pressure switch before quoting, and the inducer is one of the larger repair line items we'll spell out for you.

Wall heater or older furnace fault near the core. In the older parts of town, no-heat often involves a standing-pilot wall heater or older gas furnace. Pilot, thermocouple, or gas valve issues are typical. We can repair many of these, but on units this old we'll tell you honestly whether a ductless retrofit is the smarter spend.

Cracked heat exchanger. Furnaces of this vintage are the right age to develop heat exchanger cracks, which is a carbon monoxide hazard. We inspect with a camera and show you any crack before quoting. If CO is dangerous we shut the system down and leave you the documentation.

How we diagnose it

• Confirm the thermostat is calling and the furnace is getting the heat signal.
• Run a full ignition cycle to see where heat stops, inducer, igniter, gas valve, or flame sensor.
• Inspect and replace the filter, then check static pressure for airflow-driven limit trips.
• Verify draft inducer and pressure switch operation on older furnaces.
• Test CO levels and inspect the heat exchanger on every gas furnace before sign-off.

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

Furnace Not Heating in Martinez: common questions

Nearby and related

Furnace Not Heating near Martinez: Concord .

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