Short Cycling
When a system starts and stops in rapid bursts instead of running steady cycles. Causes range from an oversized unit to a clogged filter or failing sensor. It wears parts fast and wrecks efficiency — worth a diagnostic visit, not a wait-and-see.
The longer answer
A properly sized system runs 10–20 minute cycles, reaches steady-state efficiency, and maintains even temperatures. Short cycling (2–5 minute bursts) wastes energy on startup, never reaches peak efficiency, and accelerates wear on compressors, contactors, and heat exchangers.
Common causes: oversized equipment (the #1 issue in mild climates), dirty filters raising static pressure, low refrigerant charge, failing flame sensors on furnaces, or a thermostat placed in a drafty or sunny location. Diagnosis starts with cycle timing and static pressure measurement — not guessing.
The Seattle angle
Short cycling is the most common comfort complaint on oversized systems in Seattle's mild climate — where equipment sized for a colder region never gets a long heating or cooling run.
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