05/27/2026
The "Cardboard" Trick: Using a simple magnetic vent blocker or adjusting damper levers in the basement to force more conditioned air to the top floor. 🏠
The Right Way to Do It: Hot air rises, meaning your upstairs is naturally the hardest zone to cool. To fix this, you want to redirect the maximum amount of cold air to the top floor. ❄
Find the DOWNSTAIRS vents: Go to the rooms on the lowest level of your house (like the basement or main floor) that are already naturally cool.
Block a few downstairs vents: Use the cardboard or a magnetic vent cover to close off 2 or 3 vents downstairs.
The Result: Because those downstairs paths are blocked, the HVAC blower motor is forced to push that extra volume of cold air straight up the ductwork to the upstairs vents.
⚠️ A Quick Word of Caution:
While this is a great quick fix for a scorching summer day, you shouldn't block too many vents.
Closing more than 10% to 15% of the vents in your house can restrict airflow too much, creating high static pressure that can strain your blower motor or cause your AC system to shut down.
If you find yourself needing to do this constantly, the real, long-term fix is usually adjusting the damper levers located on the ductwork in your basement, which are designed to balance seasonal airflow safely.
