Furnace runs but some rooms are much colder than others.

Safety: Use caution when accessing ducts in attics or crawlspaces.

Steps:

• Replace the furnace filter to ensure maximum airflow.
• Check all supply registers to confirm they are open and not blocked by furniture.
• Locate manual dampers in the ductwork (often with small handles). Adjust them to increase airflow to colder rooms and slightly reduce to warmer rooms.
• If certain ducts are crushed or disconnected, have them repaired or replaced.