Furnace cycles on and off rapidly (every 1–5 minutes) without reaching set temperature

Safety: Turn off power before cleaning internal components.

• 1. Thermostat: Ensure thermostat is away from drafts, direct sunlight, and supply vents. Replace batteries.
• 2. Filter and vents: Replace filter and open all vents to reduce overheating.
• 3. Clean flame sensor: Remove and clean the flame sensor to prevent intermittent flame loss.
• 4. Professional diagnosis: If rapid cycling continues, a technician should check for limit trips, gas pressure, and control board issues.