Furnace cycles on and off rapidly (every few minutes) without maintaining temperature.

Safety: Do not move thermostats or open electrical boxes without turning off power.

Steps:

• Check thermostat location: Ensure it is not directly above a supply register, near a lamp, or in direct sunlight.
• Adjust thermostat settings: For programmable thermostats, set a longer cycle rate or lower anticipator setting per the manual.
• Check filter and registers: Ensure good airflow to prevent limit trips.

When to call a technician: If rapid cycling continues, a technician should check for oversizing, duct issues, and limit switch operation.