Furnace cycles on and off frequently, running for only a few minutes at a time.

Safety: Turn off power before accessing internal components.

• Filter and registers: Replace or clean the filter. Ensure all supply and return registers are open.
• Thermostat location: Verify the thermostat is not near heat sources, direct sunlight, or supply registers. Relocation may be necessary.
• Observe operation: Watch the furnace through a full cycle. If the burners shut off and the blower continues, the high limit may be opening. Check for airflow restrictions and blower issues.
• Professional assessment: If the furnace is significantly oversized or short cycling persists, a heating professional should evaluate duct design, blower settings, and possibly recommend staging or equipment changes.