Ask Bob HVAC and Comfort Why does my furnace cycle on and off frequently?
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Why does my furnace cycle on and off frequently?

Short cycling happens when the furnace turns on and off too often. Common causes include a dirty air filter, a clogged flame sensor, an oversized furnace, or a faulty thermostat. A dirty filter restricts airflow, causing the system to overheat and shut down. Start by replacing the filter and checking the thermostat. If the problem persists, call an HVAC technician to diagnose the issue.

Why It Matters

Short cycling wastes energy, increases wear on your furnace, and leads to uneven temperatures and higher utility bills.

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