Why does my furnace turn on but then shut off quickly?

A furnace that starts and then shuts off within 30–60 seconds is usually in lockout mode due to a failed igniter, dirty flame sensor, pressure switch issue, or a heat exchanger safety concern. The control board logs fault codes that help identify which it is.

How dangerous is a cracked heat exchanger?

A cracked heat exchanger can allow combustion gases — including carbon monoxide — to mix with the air circulated through your home. This is a serious safety concern. If a cracked heat exchanger is found, we'll recommend either repair (if possible) or replacement of the system and explain your options clearly.

Can I still use my furnace if only the AC side of my system is broken?

In a split system, the furnace air handler runs the fan and heating independently of the AC. A failed AC component generally doesn't prevent furnace operation, but have a technician confirm this before assuming it's safe to run in heat mode.

Furnace Repair — Gas & Electric Furnaces

Furnace failures have a handful of common causes — and most can be fixed in a single visit. We identify the real issue before recommending any work.

Call (714) 410-2784 Request a Free Estimate

Same-day appointments available · Serving Southern California

Licensed & Insured

CSLB Certified

Same-Day Availability

Call before noon

Free Estimates

No obligation

Financing Available

0% interest options

Local HVAC Service

Based in Yorba Linda

What’s Included

Furnace Not Heating? We Diagnose the Actual Problem.

Igniter inspection and replacement (hot surface or spark)
Flame sensor cleaning and replacement
Gas valve diagnosis
Heat exchanger inspection for cracks
Limit switch and pressure switch diagnosis
Blower motor and capacitor service
Inducer motor inspection
Control board diagnosis
Thermostat and wiring check
Flue and venting inspection

Goodman high-efficiency gas furnace installed in a residential utility closet in Orange County

Signs You May Need This Service

Furnace clicks but doesn't ignite
System runs briefly then shuts off (lockout mode)
Blower runs but no heat is produced
Error codes or fault lights on the furnace
Burning smell from vents when heat runs
Rooms aren't reaching the set temperature
Furnace is making banging, rattling, or squealing sounds

Not sure what you need? We can help.

Call (714) 410-2784

AC / Heat Emergency?

System completely out? We offer same-day emergency service across Southern California — a real person answers your call.

Call Now — (714) 410-2784

Same-day availability · 7 days a week · Real person answers

Financing Available

Ask about available financing options — including 0% interest for qualified buyers.

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Our Process

What to Expect

Describe the Symptom

Does the furnace not start at all? Start and shut off quickly? Run but not heat? The symptom pattern helps us narrow the diagnostic approach.

Full Furnace Diagnostic

We inspect the ignition sequence, gas system, heat exchanger, blower, and controls. For gas systems, we also check venting and combustion safety.

Written Repair Estimate

We explain what's wrong, what it takes to fix it, and the cost — before any work begins.

Repair and Verification

Repair completed. We run several heating cycles to confirm the issue is resolved and the system is operating safely.

Furnace Down in Southern California? We Fix It Today.

Same-day furnace repair available. Gas and electric systems serviced. Call (714) 410-2784.

Call (714) 410-2784 Get a Free Estimate

FAQ

Common Questions

Answers to the questions we hear most from Southern California homeowners and business owners.

Still have questions? Call us

Related Services

Furnace Installation Heating Services Furnace Maintenance

Furnace Down in Southern California? We Fix It Today.

Same-day furnace repair available. Gas and electric systems serviced. Call (714) 410-2784.

Call (714) 410-2784 Request a Free Estimate

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