Furnace short cycles (starts and stops frequently) without reaching set temperature

Safety first: Turn off power before removing panels.

• Step 1 – Filter and airflow: Replace or clean the air filter. Ensure all vents are open and unobstructed.
• Step 2 – Thermostat location: Make sure the thermostat is not near a supply vent, window, or direct sunlight. Relocate if necessary.
• Step 3 – Flame sensor cleaning: Clean the flame ionization electrode to ensure stable flame detection.
• Step 4 – Professional assessment: If short cycling persists, a technician should check furnace sizing, gas input, and control settings.