Furnace Turning On and Off Constantly?

The usual suspects

Overheating from weak airflow

A loaded filter or blocked returns overheat the box; the limit switch kills the burners; it cools and retries. The classic.

A dirty flame sensor

Lights, loses flame signal, shuts down — a 30-second sensor cleaning for a tech.

A thermostat reading wrong

Too close to a register or oversensitive cycle settings turn heat off moments after it starts.

An oversized furnace

Blasts the setpoint in minutes and quits — a sizing story worth confirming before spending on parts.

Stop paying for restarts.

Short cycling is usually a filter, sensor or airflow fix — quick to find with the right meter, priced upfront.

Book My Same-Day Visit

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Worth trying first (5 minutes, free)

1
Fresh filter, all vents and returns open — fixes the biggest share of these calls.
2
Check the thermostat’s spot: no supply register blowing on it, no sun.
3
Time the cycles and count per hour — bring the numbers to the visit.

Still not working? Then it’s a technician job — and the sooner it’s booked, the sooner the house is comfortable again. Book the visit →

Stop and book a pro if…

Burner runs under a minute repeatedly — stop and book; that’s hard lockout territory.
Burning smell with the cycling.
CO alarm activity — leave, then 911.
Cycling started right after a new thermostat — wiring or settings; easy fix, wrong to ignore.

Any of these? Book priority service

Next Phase technician walking a homeowner through the repair

Why homeowners hand it to us

You approve the price first. Upfront quote before a single screw turns.
Same-day service. Book in a minute, hear from a tech within 1 business hour.
500+ jobs done by 4.9★ rated, professional technicians.
Fixed right, guaranteed. If it’s not right, we make it right.

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Quick answers

Is short cycling expensive?

Twice over — igniters and exchangers age by starts, not hours, and the furnace never reaches efficient steady-state. Fixing it usually pays for itself over a winter.

Filter’s new and it still cycles. Now what?

Then it’s the flame sensor, limit switch, venting, or the thermostat — each a quick meter test for a tech. Same-day visit, price upfront.

Could the furnace be too big?

If it has short-cycled since installation day, yes — and the honest answer may be staging or blower settings rather than new equipment. We’ll tell you straight.

Done guessing?

Every short cycle wears the igniter and heat exchanger. Book the fix before the parts bill grows.