For a long time, I struggled with keeping the temperatures in my whole house even. If the upper rooms were not too hot in summer, then the lower rooms were freezing in winter. For some reason, there never seemed to be a balance no matter how much I installed independent thermostats. The house would become too uncomfortable for everyone during these extreme seasons. This went on for a few years until I figured a way out. It is possible to have the entire house comfortable for everyone, regardless of where they are at any particular time or season. My HVAC technician advice me on getting a zoning system. Experts in the HVAC industry often advice on splitting the system. I chose to go with the multiple thermostats instead of the electronically controlled dampers in the ductwork. This move solved the issue of uneven heating across the entire house. If doing this does not work, you need to find the underlying problem and fix it first. It is possible that even with a zoned system, the issue of uneven heating and cooling persists. In such cases, then other problems are responsible for the issue. Potential reasons include blockers; the fan is turned off, blocked soffit vents, and insufficient attic insulation. Whatever the point is, hiring an experienced HVAC provider is highly recommended. Make sure air flows freely through the system with no internal or external blockage. Also, confirm that there are no leaking ducts on the second floor as this could cause air loss. When it comes to insulation, make sure to go for the latest technology, meaning that old homes should be fixed.