I’ve got a 2 story house.
I’ve heard that to cool the upstairs, it’s better to seal off the return vents. I’ve got some of those magnetic cover thingies.
Is it the downstairs or upstairs vents? Or a combination?
Warm air rises, and cool air falls. Keeping in mind that if you close off too many vents you could create back pressure in the system and reduce air flow. Reduced flow might cause your coil to freeze up. That’s not a good thing.
Some folks reduce the flow of cool air to the lower level output vents and force it to the upper level. It does some of it’s job up there and then flows down to the lower level. So you might try closing off the lower return and at the same time slightly close off the outlets in the lower level. Be sure the outlets upstairs are fully or mostly open.
This should force more cool air upstairs. In the winter, do the reverse. Close off the downstairs return and reduce the flow of warm air from the outlets upstairs. Let the warm air make it’s way up there. It may take some adjustments to get it the way you like it.
How about an additional question? I have a rambler with a full basement. For the summer, I have all the basement vents closed completely. I am still getting a difference of 6-8 degrees between levels, with the basement being cooler than it should be. I keep the basement door closed, to prevent the cooler air from flowing downstairs. Any ideas?