Furnace cycles on and off rapidly (every 1–5 minutes) without reaching temperature; thermostat clicks frequently.

Safety: Turn off power before removing thermostat cover or accessing control board.

• Step 1 – Check thermostat settings: For digital thermostats, set the heating cycle rate to the recommended value for gas furnaces (often 3–5 cycles per hour).
• Step 2 – Inspect location: Ensure the thermostat is not near doors, windows, or supply registers that cause rapid temperature swings.
• Step 3 – Tighten connections: Tighten all thermostat terminal screws and ensure wires are firmly attached.
• Step 4 – Test with jumper: Temporarily jumper R to W at the furnace to see if the furnace runs steadily. If so, the thermostat or its wiring is likely at fault.