Because that is the first time in months it has been asked to work. Components degrade quietly while a system sits idle through a Florida summer — a flame sensor accumulates residue, a pressure switch sticks, a relay corrodes — and none of it shows until ignition is demanded. It is also why everyone discovers it the same week, which is worth knowing when you are waiting for a slot.

That pattern points strongly at the flame sensor. Its job is to confirm a flame is present, and when residue builds on it the furnace cannot verify ignition, so it shuts the gas valve as a safety response. Cleaning or replacing the sensor is one of the more common and less expensive furnace repairs. Repeated short-cycling can also indicate a draft or pressure switch fault, which is why it gets diagnosed rather than assumed.

The heat exchanger is the barrier between combustion gases and the air circulating through your building. If it cracks, that separation is compromised, which is a carbon monoxide risk rather than a performance problem. It is why heat exchanger evaluation and carbon monoxide testing are part of our furnace diagnostics rather than an add-on, and why a furnace repair that skipped them has not really been completed.

Please do not. A breaker tripping during the heating cycle, or a limit switch cutting out, is a protective device responding to a real condition — overheating, restricted airflow, or an electrical fault. Repeatedly resetting it overrides the protection without removing the cause. The reset is not the fix; finding what triggered it is.

A sound furnace with a specific fault is usually worth repairing. But when a Florida furnace reaches the end of its service life, most properties convert to a heat pump rather than replacing like for like — one system covers both cooling and heating, which suits a climate where cooling is the dominant demand. We will tell you honestly which situation you are in.

Not the combustion ones — no burners, no flue, no carbon monoxide. Electric systems fail differently, typically through heating elements, sequencers, relays, and blower motors, and they draw heavily, so electrical connections and breaker capacity matter more. We service both, and the diagnostic approach differs accordingly.