Furnace short cycling: causes and next steps

Short cycling means the furnace starts and stops before the home reaches the thermostat setting. A restricted filter, blocked return, dirty coil, overheating, faulty limit control, or oversized furnace can all contribute. Start with the filter and make sure supply registers and return grilles are not covered. If the pattern continues, stop treating it as a thermostat nuisance. Repeated cycling adds ignition and blower wear, reduces comfort, and can raise fuel use. A professional should measure airflow, temperatures, and safety controls before recommending equipment replacement. The repair range depends on whether the cause is maintenance, a part, duct restriction, or sizing.