Furnace starts and runs for a few minutes, then shuts off and restarts frequently (short cycling).

Safety: Turn off power before removing panels.

Steps to check:

• Replace filter: Install a clean filter of the correct size and MERV rating recommended by Ruud.
• Open registers: Ensure at least 80% of supply registers are open and not blocked by furniture or rugs.
• Check return air: Make sure return grilles are not blocked and that doors to rooms with returns are not tightly closed.
• Monitor operation: After correcting airflow, observe if the furnace runs longer without shutting off. Persistent short cycling may indicate an oversized furnace or duct issues requiring professional evaluation.