Furnace short cycles: starts, runs for a few minutes, then shuts off and restarts frequently.

Steps to check:

• Replace filter: Install a new, properly sized filter and avoid overly restrictive high-MERV filters unless ductwork is designed for them.
• Check vents: Open all supply and return vents. Remove obstructions like furniture or rugs.
• Thermostat location: Ensure the thermostat is not located above a supply register, near exterior doors, or in direct sunlight. Relocation may be necessary.
• Observe LED codes: Watch the Armstrong Air control board during cycling. If a high limit code appears, airflow or sizing issues are likely and require professional evaluation.