What short cycling is
Short cycling means the system shuts off before completing a normal heating or cooling cycle, then starts again soon after. It increases wear on compressors and ignition parts, raises bills and leaves rooms humid or uneven.
Common causes
- Oversized equipment: cools the air near the thermostat too fast, then shuts off. Common when systems are sized by rule of thumb rather than a load calculation.
- Thermostat location: near a supply register, a sunny window or a kitchen.
- Dirty filter or coil: causes a furnace to overheat and trip its limit switch, or an AC coil to freeze.
- Low refrigerant or a failing pressure switch.
- Dirty flame sensor on a furnace: burners light, then shut off seconds later.
What you can do
Replace the filter, make sure registers are open and check where the thermostat is mounted. If cycling continues, book a diagnostic. If the system is oversized, better airflow or a variable-speed replacement may help in the long term.
