Furnace cycles on and off rapidly (every few minutes) without reaching set temperature; thermostat clicks frequently.

Safety: Turn off power before removing thermostat cover and handling wires.

Steps to check:

• Thermostat location: Ensure the thermostat is not directly above a supply register, in direct sunlight, or near appliances that produce heat.
• Adjust cycle rate: On programmable thermostats, set the heating cycle rate (CPH) according to the furnace type (often 3–5 cycles per hour for gas furnaces).
• Secure wiring: Tighten thermostat terminal screws and ensure no bare wires are touching.
• Relocate thermostat if needed: If location is poor, consider having the thermostat moved by a professional.