Add a small return vent duct to each room on the second floor.
How to keep 2nd floor cool.
If humidity is the chief agent behind your second floor not being cool enough you should look into purchasing a dehumidifier.
These appliances draw excess moisture out of a room and collect it into a bucket for disposal or routed into a drain.
Locate all of the vents on the second floor and check to see if they are blocked in any way.
Fully open each vent to allow for maximum air flow.
This will block the excess heat from the sunlight.
To handle this problem there are four common ways to improve cooling on your second floor.
Make the second floor return vent duct bigger.
Air sealing prevents conditioned air from leaving the home.
Remove any furniture blocking the air flow.
To prevent the heat from rising separate the two floors with a door or curtains so your efforts to cool the second story are not lost when heat from below rises to replace any cool air.
Use a floor fan or ceiling fan to improve or direct cold air flow upstairs.
Air seal the windows in the attic and second floor.
If you allow sunlight to shine in through a window you are adding heat to your home.
Consider installing power or ridge vents to help cool the attic and provide better ventilation which also helps prevent ice dams in winter.
Slightly restricting airflow to your first floor will increase the volume of cool air to your second floor balancing out comfort.
Block off the second story from the ground floor.
Divide the house into two zones one for each floor.
Longer cycle times mean more cool air is getting to the second floor.
An excellent way to keep the second floor of your house cool is to close your blinds or curtains.
Open doors on the second floor so air is more evenly distributed when using a central ac system close doors that lead to rooms where cooling isn t a priority when using a supplemental ac unit upgrade your thermostat to a programmable or smart wifi version.
Use curtains and drapes to block sunlight.
Set the fan to be on all the time.