Definition
Short cycling is when a furnace, air conditioner, or heat pump starts and stops repeatedly without completing a normal cycle. Instead of running in steady stretches, it fires for a few minutes, shuts off, and restarts. Common causes include a clogged filter, an oversized system, a faulty sensor or thermostat, or a unit overheating on a safety limit.
Why this matters for your home
Each rapid restart is a hard start on the most expensive parts — compressors, igniters, blower motors. Short cycling wastes energy, leaves rooms uneven, and shortens equipment life. Because several different faults cause the same symptom, it's worth a professional diagnosis rather than guesswork.